Rich,
We couldn't agree more. Our 1.6 release is mainly a 'for show' release. While we feel JFBConnect is production worthy, and have received great feedback from those using the version; we're hesitant about Joomla 1.6 so far. The 1.6.3 release actually cleared a lot of issues up, but that doesn't mean some obvious things remain, and of course, more could be lurking underneath (especially security related).
Our plan with our 1.6 release though, is to get things ready for a seamless migration for JFBConnect from Joomla 1.5 to 1.6+ as well as setting up a development model (for us) that allows for feature parity (as best we can) between the releases. For the foreseeable future (remainder of the year at least), the Joomla 1.5 release will continue to be actively developed. Meanwhile, 1.6+ specific features will be added to JFBConnect. While nested categories are neat, one of the things that's widely unknown, but we're super excited about, is that Joomla 1.6 allows for custom profiles built in. No longer do you need JomSocial or Community Builder to collect additional information about your users. Just like with Joomla 1.5, we plan to have a profile plugin for Joomla 1.6 to import FB profile information without any 3rd party components. Again, there are few sites that we'd recommend should jump right into 1.6, but we are very excited about the opportunities that 1.6.3 and 1.7 and beyond present for JFBConnect.
Finally, we, currently, have no intent to split subscriptions up, so a valid JFBConnect subscription gets you access to whatever we make available. While it's a little more work on our end, it shouldn't slow down development (ideally) for Joomla 1.5 or Joomla 1.6 and beyond.. and all subscribers should be the beneficiaries of that!
Hope this explains our position. We agree a lot with you, but there is a lot of negativity toward Joomla 1.6, we're very excited about the possibilities it opens up!
Alex