I remember trying both the 19.5 and 17.5. Same issue with the Giant. And since in the end I thought the Giant was a little big, I went with the 17.5 Jamis. If you look at the geometry, the difference between the sizes seems to have more to do with the seat tube/standover height than with reach. The effective top tube (how I always buy bikes) on the 17.5/19.5 is 560mm/570mm. So a 10cm shorter stem completely compensates for the difference from 19.5->17.5. The seat tube is 2" longer on the 19.5, but seat posts are adjustable. The 17.5 does buy you more standover height at no disadvantage that I can tell.

Here are a few pics of my Coda:



Regarding the drop bar subject above, I saved this pic a while ago of someone else's Coda drop bar conversion as I thought it was interesting:

Instant cyclocross bike!