i probably would the 17" is just a little bit big for my liking, the 15" is so ideal, and i am currently on a 13" and the i5 seems to be a pretty decent processor, and has faster graphics and i believe they have upgrade to ddr3 ram? if not i probably still would
I personally love having the massive screen real estate of the 17". I've never had anything feel so expansive on a laptop before this notebook, so it's a very nice change. The size of the laptop isn't as overwhelming as I thought. I thought it was going to be a bit too much to handle on my lap (I realize how that sounds lol), but it really isn't.
I did more or less what you did, i.e., sold and moved from a C2D 17" to an i5/7 15" and I miss the drop dead gorgeous screen on the 17". But I think a big factor for your view is due to your downgrade in display pixel density. The 17" and 15" hi-res have similar pixel densities. So if you got the standard res (which I'm assuming you did), you'd find the fonts larger and perhaps a tiny bit fuzzier.
What screen model do you have? By that I mean the LG-Phillips or Samsung? Btw, look for screen calibrations in the forums. They do help in making the screen look better.