Nforcers aren't quite the same as Nvaders - the Nforcers take JT Spectra 260 lenses, the Nvaders take the "lower-range" Elite lenses, which have a narrower field of view. And yes, the Nvader usually comes with a single lense but the Nforcer comes with a thermal lense.
I quite like the protection and view that the Nforcer gives me, but damn is it hot in there! If you can, try a pair on and run around like mad for 15 minutes before you decide to buy them. Next time around I'll go for something a little more open, like a Flex 7.