Cheers for the links guys,
My honest advice (if you aren't mapping this your self) would be to go with what ever your tuner prefers. If they are happy with megasquirt then great, if not then go Omex.
In certain respects megasquirt 2 is more advanced than the omex 600, however in the real world every thing depends on how well megasquirt is built, 99% of megasquirt problems come from iffy CPS wiring and bad DIY ecu builds (which as chip says you will find lots of 2nd hand).
Which ever you do make sure you get a build thread up
Rob,