I tried XS and couldn't get used to them. Installed them adn shot them in a match and had several misses on mid and long range targets. Up close they weren't any faster for me than any other site. I thought about pulling them off then I did some more searching online, drank a little more of the XS kool aid and decided I would give them a few more tries.
I put about 300 rounds through them to try and figure out how they printed at various ranges. Then I took both my 17s to the range. One with XS and one with straight eights. I timed some strings on IDPA targets with each gun. The groups with XS sites weren't as tight (more -1s and -3s) adn the times weren't any faster.
They work for some people but didn't work for me. They will be coming off very soon.
I may try an experiment and mix the XS front with another rear and see how it works.
Also, do a search on Glocktalk. Lots of good input there