You have had some unfortunate experiences with the jdm ecu's it seems chris.
Although an EMB will give you a better tune it needs mapping, wiring in etc.. this is hassle. The ecu's such as toms, blitz, jam etc are simply plug and play which for me (and lots of other people) this is perfect.
They adjust quite well to mods imo, otherwise you wouldnt be able to run both a ct9 at stock boost on one then switch to a td04 at 1.2 and still have it fueled efficiently.
Yes there is a chance that one could run really rich on your car, but many people on here run them and ive only ever seen a few posts that they were running slightly too rich.. most of the time they are spot on.
There is an interesting article here for those registed on Uksc,
http://www.ukstarletclub.com/forums/index.php?autocom=tutorials&article=1
I think it was posted on here at one point but i couldnt find it.
End of the day if you want a high level of tune go for a piggyback like the emb or standalone.. but if you want a simple plug and play option you cant beat the jdm ecu's..