I DO prefer the preB. IF you can find one for $325 or less, they are definitely worth it. Refinishing is about $200 if you think about shipping - you only have to do this with the crappy enamel finish. $525 for a VERY nice, classic gun is not bad. If you have access to Al Oxide and can do it yourself, this is better. If they are blued nicely, $400+, because they look good as is. The aesthetic features of the PreB are SO much better than the goofy and useless squared trigger guard, and slanted slide serrations.
On the PreB, it seems that fitting the mag well is NOT that hard if you are careful - I never thought to do this with my PreB, and lucked out with some mags to fit. The DA trigger on a PreB is almost ALWAYS better, and often the SA trigger is also.
A new or OLD B doesn't matter. SOME of the oldest ones have a less durable polycoat finish - so I've heard. The sights are better, and all the cheap mags fit. But, the there is that old 80sish trigger guard. Maybe they should sell these with bell bottom jeans.
Of course there are the NonBs - I have one. It is a decent blued finish, has the new sight dovetails, and fits all mags. No needless FPB, BUT has the ugly squared trigger guard.
Have fun.