I'm 6'3" with a 19.5" Scandal 29er. With a 90mm stem it seems spot on. Unless you want to run a really short stem I suspect an 18" would be best for you.
I think they are great bikes. Nice and light. Seem pretty strong – usual XC stuff, small drops, although I haven't taken mine anywhere rocky. No / not much less comfortable than the 26er Tinbred I had before it. I think they are hard to beat for the price although I still fancy a Swift or Sir9 (would have to be 2nd hand though!) at some point.
You are welcome to try mine for size if you happen to be in the Herts or Berks area.