Sunsanvil

Less so than you might think. Because of the different seat-tube angles between the 19 and 21, you will likely end up moving the seat on the 19 back to get you in the same position relative to the cranks. The REAL difference between the frames is only a 1/4" in reach, BUT almost 1/2" difference in stack. In other words, assuming identical stems, the bars will be a little closer, but more-so lower on the 19 compared to the 21. I say "assuming identical stems" because they sort of fool you into thinking there is a greater difference in reach between the two by putting a 105mm on the 21 and a 90mm on the 19.

If you want to be more upright, on either frame, I think you'll find you need to swap stems for one with an angle greater than the 10deg stock. As long as your stand-over is good (I cant imagine it wouldn't be), you should be able to get pretty much the exact same fit on either, though given your height I'd guess it'd be easier on the 21. Trust me, I've been obsessing over this for the past year.