Since the M&P R8 uses the interchangable front sight, I would suggest that you take a look at the following link. However, I'll warn you that I've never found a fibre optic that actually works at an indoor range, not enough overhead lighting at the firing line. If you do your shooting outdoors, they are fantastic.
http://www.smith-wesson.com/webapp/w...9_757837_image
Another option is to install a reflex sight. The advantage to this is they work in any lighting because they are powered. Downside is they work so well that it's easy to become dependent on them and lose your skill for shooting with out of focus iron sights. BTW, as I've discovered, shooting with fuzzy sights is a skill that requires near constant practice. The other downside is the cost, a good reflex sight isn't cheap, however I feel that it's money well spent. Following is a link to my report on the J Point reflex.
Purchased 2 more J Point Reflex sights, range report.
Replacement Sights for M&P R8?
Linear Mode
