I just received my KAC NVG mount and it's minimally taller than a traditional lower 1/3 mount. It's certainly a compromise when peeping through the Aimpoint with the PVS-14 down but workable.

Those with experience with both, which do you prefer?

The taller height definitely makes a different when using it with NVG, especially when running a dual setup. With a single tube you can get away with a 1/3 CW mount by canting your head over and tucking your butt stock under your ear lobe, but you have to search for your RDS under a no light scenario. I'm not sure if you realize it but your RDS mount is backwards.

It's not, the KAC mount has a 45* cant to it for use with binos. Switch it around and the Aimpoint is inline with the receiver. I'm on a single PVS-14 so this orientation makes sense for me.

Cannot answer your question about KAC products, don't use them.  But any good riser under your favorite mount works well.  I use a Hahn Engineering 1/2" riser, which runs the full length of my upper.  This allows me to still co-witness with M-Bus sights (with a 3-slot Burris under the FS).  If you're a KAC fan, then rock on; I'm sure either will work just fine.

As to the extra height and using it with RDS reticle in passive mode.  Yeah it's not optimal with a micro sight.  I'm sure the EOTech reticle is the optimum choice for this technique.  But it will work.  For example if you were initiating an ambush, or other contact, you could engage passive for max surprise, then switch up to IR laser/illum, if desired.  Or if you are "danger close", otherwise known as CQB distance, you could switch to passive for max tactical advantage.  Again switching back to IR laser/illum when appropriate.  This is a very specific technique for Peer-to-Peer engagements.  This is not your go-to technique.  Would not base my RDS choice on it.  

As to using this for "positional" shooting.  Yes, it does require the use of another position, different from traditional cheek weld.  But it's not an issue, once you put the reps in.  Just another way of doing it.  My buddy was a SF sniper instructor and has no problem shooting prone, kneeling, etc, with an extended height Red Dot or other scope.

All in all, I love the new height.  It just works better for me, overall, regardless of RDS use.  But granted, it is an optimized technique for those shooting in dynamic, fast-moving gunfights.  If this is how you see yourself possibly fighting, then check it out.  Sorry about the thread drift.  KAC, right on.  Carry on.