Does anyone feel that there is a certain handlebar height where you should not use neoprene riser bushing and use a rigid mount to reduce any flex that might be encountered because of the taller bars? Or should you try it out with the neoprene bushings and if you get to much flex, then switch to rigid mounts? I had 16" apes on my Springer but never really noticed any flex. But since I am converting my Bob to a WG front and running 16" apes my bud says he wouldn't run them with rubber bushings. Any thoughts on this?

 

I've never tried it, but I wouldn't think rubber would be worth a crap with bars that tall.

 

Everytime I have changed my bars or even removed them for any reason I have switched from the stock bushings to the polyurethane ones. Did it when I put 16's on my Dyna, did it when I took my SG bars off for powdercoat, same when I put beach bars on my old Road King and before that when I drilled my old FLSTF bars and internally wired them. Can't say it was a huge difference on the SG (had the bike for less than 4 months when I changed 'em out) but now I don't have to worry about them wearing out.
The ploy bushings provided a huge difference on the Dyna, wnet from about 1-2 inches of slop to being rock solid.