Don't think you would have a problem reaching the button to release the sight to flip up.  However, since the 9395 tightens with setscrews from the bottom you would have to drill access holes in the bottom rail of the 9.5 FSP to tighten the setscrews.  Also, the 9395 has a pretty hefty profile on the bands that encircle the barrel, I'm not sure it would fit inside the rail.  I haven't installed them together before so I'm not sure, maybe someone out there has tried it and they can chime in.

Jason

It would work great with a PRI flip up as the set screws are on the side where there is material cleared to get to them like the taper pins.  The DD FSP rails are great products and I like them, but they are a little tedious to install  Here is a pic of a 9.5 with a standard sight tower, along with another upper with a yhm front flip up.