In my simple minded opinion, it would depend on how I intended to use the camper. If I'm going to do a lot of boondocking, needing to run the generator for long periods of time, I'd choose the separate Red or Blue gas powered generator. Less noise and less fuel usage.
Now, if I just want to use it occasionally and just for short periods of time, the propane one is handy as it's all built in and all you have to do is push a button to use.
We have one in our Lance, I've played with it a few times. It is loud and it does vibrate the camper somewhat. The longest time I used it was when our power at home went out. I fired it up and plugged in the freezer, fridge, satellite and TV in the house for 8 hours.
