No one seemed to want to comment on BeerSmith vs Beer Tools, so I went ahead and paid for Beer Tools. Here's what I think so far:
Beer Tools has a nicer outward appearance - I like the pint glass color estimation. It reads BeerXML, so I can import my BeerSmith recipes. The style widgets are nice (sort of a bar graph appearance), but largely unnecessary - I'd rather see the "Analysis" info in the same tab. Adding ingredients is a pain. They are sorted only by name or supplier, and the interface is a bit clumsy. I'd like to see more info in the ingredient dialogs (color, typical use, potential yield, etc). It took me a while to figure out how to get to the mash schedule portion, and I don't like it much either. Other bothersome issues include having to open multiple windows for each recipe and its tendency to flicker/flash when it needs to update displayed info (like it's "repainting" the entire window when only one or two things change).
So far, BeerSmith keeps my vote.