Both are fairly profitable, however the bulk of our income is via HeavyMETL as we can get customers that are willing to commit to big contracts (>$1MM/year). Bx was a labour of love, because I too did not like the existing bookkeeping packages.

We're going to be releasing an improved version of Bx with some additional project management and task management functionality, so stay tuned! It's going to be a pretty awesome addition to the basic project management stuff on there already, so be sure to check back in a month or two :)