The paid for version of AGENT ($99) is now up to 1.4.1.0. If you look at the version change-log since 1.1.X.X there has been many bug/crash/hang fixes.
However.. I have been running it for days and have not experienced any major crashes... except the following which I can live with...
1. The initial search for VSTs did crash for me (I have about 200+ VSTs and it got stuck half way through). However, as reported earlier in this thread, if you re-run the search again (and possibly again and again) you will eventually get through it. Ok - that's annoying, but worth the patience. It will popup at the end with a list of VSTs that it didn't like - however, what is funny is that it listed a whole bunch of VSTs that I have opened in AGENT and they run totally fine - so ignore the warning list.
2. Don't try and load VSTs into AGENT whilst your sequencer is playing. Reason has crashed a few times when I did this. But seriously... I shouldn't do that and can easily stop myself doing it!
PLUS... it isn't just about using LESS CPU for each instance of VST you are running. If you read my comment at the beginning... you will use ZERO CPU if there is no audio running through your effect VSTs. So - used carefully and thoughtfully, you can add 10s, maybe 100s more VSTs than you could before. So the $99 cost for the bug free version is worth considering me thinks.