Spandex for Sony HW30?

With a "Scope" screen's reduced height, (...mounted down further from the ceiling and up from the floor...) and if both room-based reflections and ambient light are under control, you will still need to use a silver Spandex, one with a slight degree of sheen. Your screen size and throw distance, combined with the Sony's lower lumen output, requires your surface to be at least 1.5 gain just to achieve 12 foot lamberts...and that's not even considering the drop in brightness you'll get if 3D is engaged.

Moving the PJ up to 14'-4" will help considerably. Cutting back screen size to a maximum of 115" diagonal in 2.35:1 even more so.

You'll have to explore your options as to just how ideally suited your plans are to your realities. The Sony...quite frankly, is you biggest limiting factor in it all.

the only potential (and i say potential because i have no clue of the AT properties or what the actual achievable gain is and i think you would need to mount at eye level) seems to be to look into some of the metallic-coated spandex, if you can mount the PJ at eye level. in my brief experimenting with metallic coated spandex it seems to have something like 1.2 gain, maybe more, but only when projecting at eye level. just a thought if you were up for experimenting...

Do you find any hotspotting, irridescent shimmer or other distracting artifacts with stuff like silver spandex?

a little bit when off axis up and down, which is why i mentioned at eye level i think this would be fine. but i really didnt test it a ton, so i dont want to promise anything. it did look promising though.