I'm 5foot 11 inches and my twenty inch bike has a 21.5 Top Tube.
I had an S&M Holmes (still do, just not built) that's a 22 TT, and now I have an Indust with a 21,5/8ths TT.
The Homes felt just a little bit too long for me. I think it has to do with it having a lower bottom bracket too, but 22 was just a little bit too much on this bike.
The Indust feels pretty much perfect since it's got a slightly higher bottom bracket along with the shorter TT.
I've had a top load stem and 8.5 bars on both bikes and it feels pretty perfect.