I'm thinking about buying a Camelbak Mule or Mule NV. Does anyone have a view as to whether the NVIS backpack panel is worth the extra cash?

Osprey Raptor is the one to look at…

Was going to get the NVIS (2010?) but picked up a mint 2008 off the bay for about £20. The newer one does seem funkier but TBH my one does the trick for me. Still haven't worked out how to make it sit right – kind of digs in around the top a little. But other than that it's sound.

I've got the nv version tbh I tend to take the back plate out because I find it fills up half the space in the pack. I don't really notice much difference sweat wise either.

I picked up an 09 nvis for less than the normal one, it's comfy, and vents well on my back, but I've not tried the normal one to compare. Only downside is the extra weight.

I had an Mule NV. The back panel did reduce the sweaty back thing but the hard plastic bit dug into my shoulder blades, and it was heavy compared to the standard Mule.
Now using a North Face Hammerhead which I really like.

I've recently upgraded from a mule to a mule nv. The NV is deffinitly cooler but it is heavier and the nvis system does reduce the useable volume of the pack. I did think it was less comfy than my old one, but after three months with it i wouldn't ride with anything else (although would like to try one of those wingnut packs)