I am using 0.91 and it's very stable for me. I use it daily, usually all day long..
I will say that the developer does NOT use a blackberry and has been known to introduce 'instabilities' into future versions. For this i keep the stable version and upload a new version as a 'beta' for testing only.
The prior stable version for me was 0.82.
Please e-mail the developer your problems, he is working on stabalizing the program and could use your feedback.
I have 0.88 on my 7520 and it locks up when you try to connect. The BB eventually closes it due to a queue overflow. This is the only version I've tried so far, I might give 0.82 or 0.91 a try since you've had luck with them. I have WLirc running and it works so I have a working option for now.
Version 0.92 is very stable on my 7230. I'm using BWC on T-Mobile.
I was running Virca, but prefer the features and stability of jmirc. I've set the backbuffer to the maximum 999 lines, which is handy for fast moving chat channels.