Yeah, I wasn't pleased with 6.0, either. I HATE 18.104.22.1684, which is what came pre-installed on my 9700. It seemingly looks for ANY excuse to display the hourglass/spinning clock face and lock-up! And not just for a couple seconds here or there, but for 5-10 minutes OR MORE at a time!
It also does NOT like the threaded text messaging that RIM came up with, which they've forced upon us, which we CAN'T turn off! It REGULARLY locks-up my text messaging in the middle of a conversation, refusing to open the new message. It will stay locked up like that for quite a long time before I can open the text message.
So, I have no idea if 6.0 fixed those issues or not. It's such a memory hog that I removed unnecessary apps, leaving about 11 MB of free space available, and within just a few minutes, something ate up that 11 MB and it was showing 0 MB free!
Combine that with my custom ringtones not working, and I quickly rolled back to 22.214.171.1244... and found myself with 65 MB of free space after the reinstall!!!
But I still have the same problem with text messages, so I've now rolled back even FURTHER, to Version 126.96.36.1996. If that one's still bad, I can even do one further rollback. I'm hoping I don't have to.