I had a really hard time with this too. I went back and forth a few times before finally deciding on the PRI. My biggest issue was that I thought it looked bulky compared to the Troy...who is bulky in the same right (when compared to...say, a KAC sight), but not quite as bad. The big deciding factor for me was that I didn't care for the "paragraph" of writing that is on the front of the sight block.
After ordering the PRI from Talon Arms, I firmly believe that I have made the right choice. It has great lines and the pictures of it on these forums really make it look bulkier than what it really is. Paired with my ARMS #40L, it makes for a beautiful co-existance. The build quality is everything that you would expect from PRI and the machining and finish is top shelf.
If you can overcome all the marketing BS on the front of the Troy sight and the slightly bigger mass of the PRI, I don't think either one would be a "wrong" choice.
Good Luck.