I also voted eight--I have personally had practically no problems with any of the b60+ releases. The few problems I have had are generally minor:
-A graphical glitch that seems to be limited to Macs
viewtopic.php?f=21&t=10637-A very minor UI bug that I noticed a couple days ago and have just reported
viewtopic.php?f=21&t=12507-One of the players in my group receives strange error messages intermittently; I haven't been able to sit down with him to try and figure out what triggers them, and they're not common enough that they have impacted gameplay, so I haven't reported them.
-An overall feeling unpredictability. Every so often in MapTool, something will not work the way I would have anticipated (e.g. the steps required to select a transparent color in the drawing tool). It's not that it malfunctions or crashes, but I personally never feel 100% confident in a program until the UI is solid, because the UI is my only visible indication of the developers' attention to detail. If the UI feels slapdash, then I'm going to assume the underlying code has problems too. MapTool's interface is overall pretty good, but there are still some quirks, and as long as I feel like I'm adapting my usage to the program's quirks, I will always be a bit wary of what's going on under the hood.