Sure, I've just sold one actually......Mine weighed 560g. The chin protector can be removed with a couple of pennies, so it can be turned into a standard XC helmet pretty easily.
It does offer good protection for the jaw, basically it would simply save your teeth in a full face smash, but not protect your face in the same way a Full Face would.
I've worn a FF before, and the biggest thing you will notice is that you can actually breath normally when climbing on your bike, instead of feeling like you are at altitude as you are breathing in sh1t loads more CO2 than normal. Ventialtion is awesome, obviously the same as a standard XC helmet.
Its a 'one crash only' helmet though, with a FF if you have a fall and bash your lid, you can usually, obviously depending on the damage, use it again. With the Parachute, the front protector absorbs a lot of the impact and crumples around the sides. Although MET do offer a 50% replacmement.
I've seen someone stack with one, it saved his teeth, he only came away with a cut cheek and a black eye, and it was a nasty crash....but the helmet was a right off.
Another option, (not sure if you can get these in the US) is the CASCO Viper. same helmet used by the German Fire Service. I used one for a week in Spain. Pretty good, and the chin guard can be clipped and unclipped on the fly. The chin guard on this one was a lot more substantial. Weight was about the same as the Parachute, maybe a little more. Ventilation not as good as the Parachute either.