Yet another orphaned Thoth user here. Man, I hope somebody picks up the slack eventually, as that's one heckuva newsreader and I hate to say "Well, you should be using Thoth, but...".
That software dropping always bugged me a little; if he was considering completely ceasing development, including cutting off all new purchases, he could've given us existing users an option to "renew" our licenses at full or half price to encourage development (heck, he could've re-numbered it version 2.0 to make people feel better, if he wanted). Sure, we'd have been paying for nothing, so to speak, but I'm sure I and others would have been quite willing to pay to encourage continued development on the app--certainly better than nothing at all, which is what we got.
Unison isn't that bad, actually--if it weren't for Thoth, I'd be using it and probably not complianing--and seems to be improving slowly. If version 2 eventually ships with some of the features I've heard discussed, it'll definitely be worth another look.