I have a JPoint (Trijicon) that has been mounted on a FA97 .357 Mag, FA83 .454, and a FA83 .475.  I have 63 year old eyes -- distance no problem, but front sight clarity needs adjustment -- 1.25x to 1.5x.  Anyway, I've experienced dot flare with the JPoint under differnt sun positions and with differnt glasses -- it shouldn't but it drives me crazy.  I've had a love/hate relationship with this red dot ever since I bought it.  Offhand Performance for me depends upon the gun -- .454 works great -- the .357 and the .475 are problematic.  I think this is due to the different trigger pulls on these guns.  I shoot best with a 3.5 to 4 Lb trigger and the latter two guns are in the 2.0 lb range -- don't know why. 
I have two 475s that are virtually identical except for trigger pull -- the one with the JPoint is 2.5Lbs, the open sighted one is maybe 3.5 - 4.0 lb -- I can consistently shoot the opent sighted gun much better offhand.  From a rest the JPoint gets the nod.
 
With that said, shooting the gun from a supported position these sights are great.
Paul