Hi Robert,
You have asked a lot of good questions, many of which have been the topic of lively discussion in these forums. I'm happy to impart what information I have, which is by no means exhaustive but I hope it gives you some place to start. Searching the forums will yield a treasure trove of additional information. Much more than you can digest in one sitting, believe me.
There are a few hushbox solutions for fan noise. The original G15 definitely needs a hushbox if it is anywhere near the listeners. There are many threads on hushboxes that you can search. There is long thread discussing Mark Foster's recently built (and beautiful) hushbox for his G15. There is also a company called whisperflow run by Dave Beatty here in NYC that builds hushboxes for these projectors. Aside from the fan noise, the hushbox must be able to dissipate the excessive heat given off by these projectors.
I cannot speak to the fan noise level of the G150CL since I have not heard it, but someone posted a review recently that might give some helpful info. I have not seen any relative technical decibel level info anywhere.
As for the Panamorph, it is one of two anamorphic lenses that are discussed heavily on this forum. They are differently designed but both lenses take the 4:3 picture from a 4:3 projector and convert it to a 16:9 format. Their benefit is many fold. They enhance resolution by allowing the use of the entire D-ila panel. Without the Panamorph, in order to view a widescreen source, you would have to decrease the resolution of the panels (turn part of the panels off to make a 16:9 from the native 4:3 image). They also enhance brightness by allowing the use of the full panels. For more info on the Panamorph go to
www.visr.com. Whether you need the Panamorph or not is a personal decision. It enhances the theater experience in the ways I've just discussed, but it is not essential.
If you have a good scaler, you can leave the Panamorph in place full time. I do. And once the projector is in place, you do not have to move it.
The range of prices you quote for the plasmas are retail and don't reflect the street prices now. The 42" panny can now be had for under 5K. A 50" plasma can be acquired for under 9K. I bought my panny from Paul at Projectorone (he's now with visualapex.com). He happens to be located in Seattle and was terrific to work with. He gave me great advice, a great price and excellent follow-up customer service. Many people on the forum have purchased plasmas from him with very positive experiences.
As far a masking is concerned, I did not bother. My electriscreen is a 16:9 aspect ratio, which is native for high def and most DVD movies. There are very few high resolution sources that are recorded in 4:3. Some movies are recorded and shown in 2.35:1 widescreen, which when shown on a 16:9 screen do have black bars above and below the picture. It does not bother me.
I am using optical glass from Edmunds optics for my G15, which is mounted behind my back wall. It works very well as both a sound insulator and allowing the light to pass through it without any noticeable effect.
I hope you find the above useful. If you would like any more info, let me know. You can post or send a PM. If you are lucky, others with much more knowledge than I will jump in here.
Good luck.
Alan