I think this is really funny. I've used a lifeproof case as my everyday case since I got my 4S almost two years ago. I love the lifeproof case and I really love the waterproofness. I've taken my phone into the pool and the ocean (and even the shower) and I don't have to worry about it.
However, I do not love the screen protector. In my opinion the screen protector is one of it's biggest weaknesses... It doesn't adhere directly to the screen, so you get some touch sensitivity issues and some screen distortion issues... Moire patterns and such. If you look at the Fre thread on here you'll find lots of complaints about the screen protector.
I haven't used any of the other waterproof cases, but from reading about them it seems like the screen cover is a common complaint. I think it's great that lifeproof was able to get rid of it and I'm super excited about this new case. Clearly it does expose the screen to the possibility of scratches or other damage, but other than an occasional trip to the beach I'm rarely in a place where I would have to worry about that. If you spend all day digging in the sand then maybe putting up with the screen protector on the Fre is a better option for you.
Also, as far as installing screen protectors with the nuud case, it's worth noting that the screen protector that comes with it is much smaller than the iPhone and is meant to be installed *after* the case is installed. They want the case to be sealed directly to the phone's glass and then the screen protector will cover what's left exposed. The ipad nuud case is the same way. It doesn't come with a screen protector, but the 'lifeproof approved' one is an invisishield protector designed to fit only on the exposed glass after the case is installed.
I'm sure you could any screen protector as long as you cut it down and install it after the nuud case is installed so it doesn't interfere with the seal, but trying to install the nuud case with a regular screen protector may be difficult due to the tolerance issues and would also make me concerned about water intrusion.