pixel size of 1600x1200 15" and 1920x1200 17" should be just about the same
You really need to look at the fonts yourself to judge, it depends on your eyesight; the text won't intrinsically be blurry.
I had a 1600x1200 15" and used large fonts most of the time, and the next laptop I buy will be 1400x1050.
I just got a 1680x1050 15.4" for work last week, and I've gotten used to it with normal-sized fonts already.