been having the same dialema (sp) myself recently as im going to be selling my e30 soon, m3 or back to jap turbo ? i've owned 3 e30's, and an e28 m535i, 2 s14's and and an r32 gts-t.
i test drove an r33 gts-t the other day gave it a couple of little drifts and now i've totally decided thats what im gonna go for as it drifted effortlessly in the dry compared to my bmw's (admitedly my e30's all had open diffs and the e28 had an old worn sport diff) and in my opinion jap RWD turbos just feel more right for the job to me
although i've never drifted an m3 although i have driven one.