I can understand your point of view, but let’s clarify a bit : as far as the SmallBiz version is concerned, I fully agree with you it’s the same app with a better interface (that’s not a small pro, IMHO).
Now, if we’re talking about the "Corporate" version, well there are a few important things : the calendar (will be great to have my projects into iCal

), a basic ticketing system, Time tracking (very basic but a key feature for me !), and Pages which have wiki-like features (revisionning) and can allow collaborative editing of documents (it’s not writeboard, granted, but decent enough).
I have lots of doubts about projectpier, checked them out but I fail to see clear vision (where do they want to go with this fork ?). I share what kemie posted at their forums (
here) and the answer is quite fuzzy...
Personnally, I don’t think aC 1.0 is that expensive. Of course I am a big fan of Open Source but when you have no serious alternate OS app, I’d rather go commercial especially when it’s a tool I use every day. Being french, I can’t turn to hosted solutions such as BaseCamp (not translated) or Joyent’s connector

The corporate aC 1.0 seems a very good option to me, especially since I get to keep all my projects data currently run with aC 0.7.1.