Well when I demoed the screen it was vs a normal white and another grey screen, difference was night and day to myself and the mate I took along but you are also paying for a screen that won't crease, falter over time. Aside from the main factor that most people can't really watch a projector without all the lights out, curtains drawn so don't bother going down that route, this is specifically designed to take away those shortcomings.
With regards to the PJ, I haven't seen the HD30 in action but I believe they are a class apart judging from reading over on AVForums.
Its one of those things you need to demo yourself to decide if its worth it for you, I didn't want to compromise on the 'Living Room' aspect of where the PJ will be so am willing to pay for it. But in comparison to a 65" TV it's not much more of an excess cost wise unless your going for a bargain basement 65".
Light fixtures can always be changed OP but not gonna try and convince you, if you want one you'll get one