I purchased Logos 8 a couple of days ago, and I must say I like it. I have had not trouble with crashes or hangs.
I use Logos all day, every day. However, I don't use most of the features. I mostly do searches and commentary work.
The stand out feature is that is is snappier. This is the Logos I have been looking for. The upgrade is fairly inexpensive. I'd encourage you to take the plunge.