the biggest is the fact the 94-95 is load based and not rpm based...this load is based on the MAF readings and why it is SO VERY important to get a good tune that can get this figure correct.
there are a bunch of fine diff. over the fox ecu.
As far as swapping...its like going from a pentium (one or II) to a 486. It will get the job done and the a9 works well...but once tuned the 94-95 eec is realy quite the good ecu.
Agreed. It would be not unlike going back to carb from an A9 series puter, for simplicity of tuning if not wanting to use computer-aided tuners/chips.
If doing the swap, you would need things like a fan controller, BAP sensor, etc. I would rather tune the existing systems, since it is a much better processor (like BlkSN said) but it is fed a crappy factory tune.
We assume you have a stick too (or a bigger can of worms is opened).
Good luck with the decision. This type of conversion is or was called a PIH kit/conversion (if you desire to search about it).
One thing worth mentioning also, is if your car is equipped with the AODE transmission, you also need an add-on transmission control device, since the 94-95 EEC handles that duty. I'm not sure what they run, but in my opinion the additional cost of those, plus the PIH kit sort of negates having made the conversion in the first place, since you're still running a factory computer with a factory tune, and will more than likely need a tune down the road when the mods follow the conversion. It might not be a bad idea to read up on some of the self-tuners like the TwEECer or PMS. There's a TON of guys running those with great results and a good tune that spent less out of pocket than going with the PIH.