I can't actually see any real downsides to anything myself.
I paid for a year up front, and I own it at the end, and along the line we got some great enhancements and fixes. Using the old model, sure - we get some bug fixes and sometimes extra features over the product's life cycle (what, 3 or 4 tops maybe?), so like them or not, we've been getting a LOT more stuff over this year, and the fixes have come far more regularly.
Sure, that also means that the chance of bugs sneaking in more regularly, but think about it for a minute - if you get an update in February and it's got some nasty bug, and you have to wait until April to get a fix, like could happen in the old model, how is that any better than getting a bug in February and getting it fixed in March, or even sooner (as happened with a bounce bug a while back - that was fixed in a matter of days and a patch posted online) like we have now?
Not all of the features appeal to me and there's still a few annoying quirks and things on my wishlist that I'd love to see implemented, but I think overall, this has been an outstanding success. Definitely renewing after my 12 months is up!