ZHP's are nice, I test drove a 330i ZHP a few months back, along with some regular 330's, including a cabrio. The ZHP was sportier, it had a SSK already which was great to shift with. I could tell a 'slight' difference in speed, it did have a bit bumpier ride, but it was much tighter cornering(a tradeoff).
If I could shop for a new 3 series (non //M) it'd be a ZHP, certainly.