I'm 5-7 and I find my size 16 very comfortable in this form, although I might not be so keen on the eBay set up with an Indy fork, no stem stackers, a long flat stem and a flat bar. That kind of retro position is too low for me and if a bike is low at the front, it can begin to feel too short IMPE.
The only thing I don't like about the basic frame design is the short (9cm) head tube, but 2cm of extra spacers don't really make any difference to the way a bike rides. In theory I am inside the height range for a size 18, and above the height range for a size 16, but personally I find the 16 much better. One thing is that a shorter wheelbase makes the steering livelier. But that's just me, others may well differ, and 5-9 may be too much, I don't know. 5-9 is right in the middle of the size 18 height range according to Kona.