Go with the Expansion Dock + the Ethernet Expansion. This way, if you flash a buggy OS build, you will be able to recover much more easily.

The mini-dock is small and compact but does not expose any external connectivity other than the micro-USB for power and the standard USB for USB device(s) (e.g. memory stick).

The standard expansion dock is larger and does expose some (but not all - see below) of the Omega's pins. In particular, it exposes Serial pins, I2C pins, Ethernet as well as the GPIO pins while still providing the the micro-USB for power and the standard USB for USB device(s) (e.g. memory stick).

You may also want to consider the power dock if you wish to run your Omega standalone without an external power source.

From my perspective, there still exists a gap in the available dock facilities for the Omega.

• The mini-dock does not make any of the standard Omega pins externally accessible without soldering directly to the Omega or mini-dock headers.
• While the standard expansion dock does expose a significant fraction of the Omega pins, not all of them are exposed
  • this is particularly so for the Omega2 which as well as pins for I2C, it shows groups of pins for SPI, and I2S well as 2 serial connections and ethernet connection

This lack of exposure is exacerbated by the fact that the Omega and mini-dock header spacing is 2mm which makes it harder to mechanically connect to more standard (more readily available) 0.1in headers and breadboards.

The standard expansion dock is primarily designed to provide access to existing expansion boards that don't need the full access of all of the Omega pins

What I would like to see is a version of the mini-dock that exposed ALL the Omega/Omega2 pins in standard 0.1 in headers. This would give some greater connectivity and while being larger than the existing mini-dock could still be significantly smaller than the standard expansion dock.

The issue is muddied by the fact that the available documentation on the pin out for the Omega and the Omega 2 differ from each other particularly in relation to the pin numbering.

Not withstanding that, the Omega and the Omega2 have 32 pins while the Expansion dock header has 30 pins.

Looking at the Omega only (what documentation is available for the Omega2 says the pin out is subject to change) it would appear that the Omega has GND on two pins and that all the rest are unique. Thus giving 31 distinct pins.

The expansion dock header duplicates the following pins:

• GND on 3 separate pins
• 5V on two separate pins (Noting also that 5V is NOT a pin on the Omega itself)
• 3.3V on two separate pins

Thus totalling only 25 distinct pins that correspond to one of the 31 distinct pins on the Omega - i.e. there are 6 Omega pins that are NOT broken out on the expansion header

But yeah: before doing more things around the pinout in the campaign we should wait for the next Update

So a list of pins not broken out:

• FW RST
• IO 15
• IO 16
• IO 17

so in theory, you loose 3 IOs. They could have broken them out if they had removed like one GND Pinout and one 5V/3.3V.

Omega Pin 	Expansion Dock Pin
=============   ==================
GND - 2 times	GND - 3 times
VOUT/2.8V	2.5V ???
26	        26
23	        23
17	        no pin
16		no pin
15		no pin
14		14
13		13
12		12
8		8
7		7
6		6
1		1
0		0
RST		RST
	
VIN/3.3V	3.3V - 2 times
USB/D+		USB+
USB/D-		USB-
Serial/TX	no pin
Serial/RX	no pin
FW RST/11	no pin
VOUT/2.0V	2V
Ethernet/TX-	TX-
Ethernet/TX+	TX+
Ethernet/RX-	RX-
Ethernet/RX+	RX+
18		18
19		19
I2C SCL/20	20
I2C SDA/21	21

no pin		5V - 2 times

So, as you indicate, there is no Expansion Dock pin for the following Omega pins:

• FW RST
• 17
• 16
• 15

Though I am still unclear as to any access on the Expansion Dock to the Omega pins:

• Serial/TX
• Serial/RX

The situation is further significantly complicated by the fact that from what has been available to date, the Omega2 has some significant differences in it's pin out compared to the Omega to the extent that one wonders about the compatibility between the Omega and the current and any future Expansion Dock and between the Omega2 and the current and any future Expansion Dock

For reference, the following is what differences I have been able to deduce between the Omega and Omega2 pin usage:

Omega Pin 	Omega2 Pin	Differences
=============   ==========      ===========
GND - 2 times	GND - 2 times	None
VOUT/2.8V	11	        Usage
26	        I2S CLK/3	Functional and Pin No
23	        I2S WS/2 	Functional and Pin No
17	        17	        None
16	        16	        None
15	        15	        None
14	        Serial RX1/46	Functional and Pin No
13	        Serial TX1/45	Functional and Pin No
12	        SPI MISO/9	Functional and Pin No
8	        SPI MOSI/8	Functional
7	        SPI CLK/7	Functional
6	        SPI CS1/6	Functional
1	        I2S SDO/1	Functional
0	        I2S SDI/0	Functional
RST	        RST	        None
	
VIN/3.3V	VIN/3.3V        None	
USB/D+	        USB/D+	        None
USB/D-	        USB/D-	        None
Serial/TX	Serial RX0/13	Functional and Pin No?
Serial/RX	Serial TX0/12	Functional and Pin No?
FW RST/11	FW RST/38	Pin No
VOUT/2.0V	VOUT/3.3V	Functional
Ethernet/TX-	Ethernet/TX-	None
Ethernet/TX+	Ethernet/TX+	None
Ethernet/RX-	Ethernet/RX-	None
Ethernet/RX+	Ethernet/RX+	None
18	        18	        None
19	        19	        None
I2C SCL/20	I2C SCL/4	Pin No
I2C SDA/21	I2C SDA/5	Pin No

Different functionality and pin numbers in some case will require specific versions of code for each of Omega and Omega2 that use the pins that are different.
This covers the following set of pins:

• On Omega: 26, 23, 14, 13, 12, 20, 21, Serial/TX, Serial/RX
• And correspondingly on Omega2: 3, 2, 46, 45, 9, 4, 5, SerialRX0/13, SerialTX0/12

In addition, on the currently available information, I have concerns over the differences on the following sets of pins:

• Omega - VOUT/V2.8 ; Omega2 - Pin 11 : Nature of pins completely different
• Omega - Serial/TX and Serial/RX ; Omega2 - Serial RX0 and Serial TX0 : Opposite sense of TX and RX
• Omega - VOUT/2.0V ; Omega2 - VOUT/3.3V : different electrical characteristic potentially affecting connected external equipment

One final comment on all this in relation to pins 15, 16 and 17:
While these pins on the Omega and Omega2 are not exposed on the Expansion Dock, they are used on the Expansion Dock for control of the expansion LED:

• Pin 15 - LED blue
• Pin 16 - LED green
• Pin 17 - LED red

However, note also that with the Power Dock there is no LED and so these pins are neither used nor exposed. It seems a shame to have 3 pins not exposed just to control an onboard LED that isn't always available