Okidoki, No decent pictures yet, but I have assembled the board, got the arduino working at 8Mhz (IDE tricks, I'll document). I'm only running at that because I have several 8meg crystals and this is an ideal project to use them up. Speed is not a factor here.
I've tested the LCD, but still need to test the mosfets, speaker and all other ports, a conductivity test with my multi-meter showed no faults or shorts. The unit also powers and runs off a 24v supply with no problems.
One Issue is that I forgot that manual resets are a 'thing', so I'll probably add a connector point for a reset pulldown switch before I publish., there is plenty of space in that area of the board.
I also see bigger changes I'd like to make for the v2 board, which is theone I intend to build for my home aquarium. I will move the CPU more central to give more space around it, duplicate the I2C and Onewire port connectors, bring out even more 'spare' io lines, possibly add an ISP connector. But I plan to keep the power in/out connectors and FTDI in the same place, and keep the same 70x70 mountholes and 80x80 form factor.