Stoked with my G4. I had a G3 before but with downsizing decided to go for a new container too. Basically everything I was happy with on my G3 is sound, and the grumbles are gone! The spacer foam is really good, holds it in the right place for FF. I also ordered the unisyn harness with lumbar support, which hugs my body really well.
The service from Mirage was great. I was able to get the original details from my first rig so I could compare sizing - useful, as my own measurements (taken 3 times!) turned out to be the same as the G3 so the size would have been a touch out. Discussion with Ward at Mirage helped me sort this out.
I didn't get the split bag (have to confess don't know whats going on there) but no probs so far.
Not due a third one for a while but I know where I'll be looking!