Traded my E39 for an E30. Like it a bunch, bone stock 325is. Drove a NA 944 and will agree with ddavidv that I was left expecting more.
Check out the Mid-Atlantic E30s on FB. Clean cars are abundant and trade for around $2k for stockers to $5k with very tasteful engine swaps. Group is very active and I know there are guys as far north as NJ. You may find a willing trade on there as well.
To clarify the Trans in the 944s / vs the 951. It is not the trans that is the issue it the R&P that is weaker in the NA cars.
=Long answer=
ive had an e30 M3 for a rather long time, an e30 gutted challenger, and have been driving a new to me 87 944 SuperSoft for the last 6000 miles.
when i get out of the 944 and into my M3 i realize a couple things i HATE about e30s and one big advantage.
-first is that seating position in an e30 can feel pretty good but coming from the 944 the location of the pedals and steering wheel are a LOT better. i'm too close to the pedals to get close enough to the wheel in e30s, though i'm going to fix that with a different hub/wheel.
-second is that the location of the seat in the car isnt centered with the steering column... like at all. a problem i fixed in the challenge car by making mounts that center it. it's something like 1.75" if i remember and i dont notice it after a couple days in the car, but it bugs the crap out of me when i get back in the stock seated M3 from the 944.
-the steering wheel angle is fairly high in the e30, so i might need to lower the column a bit when i extend the steering wheel closer to me to correct the height.
-despite the kinda big 2.5L engine my 944 feels SLOW, like miata slow without the nice revvy reward for winding one out. i find that i dont care when i'm DDing it and i love the shifter feel but after swapping the M3 feels like a rocketship and makes sexier noises. even the 325is makes nice engine noises and feels significantly faster. also the 5th gear in a NA 944 is so tall it hurts.
-the e30 sport seats and M3 in particular are excellent if not beat up (mine have 160k and are pretty good), with good lateral support, lumbar that fits me, and head rests that work with and without a helmet, compared to the 944 seat that bugs my lower back after about 45mins and lacks the lateral support (i'm fixing that with a set of cayman s seats i bought).
so the overall ergonomics i find to be in the favor of the 944 stock for stock, but it's hard for m3 to compare the driving dynamics as my 944 is VERY soft and sloppy compared to e30s which handle much tighter. i will say though that even the soft 944 setup had me really enjoying tossing it around because it feels like a better balanced car out of the box so i'm excited to see what mine will do with a mild suspension upgrade and double the power.
=short answer=
you need both