remember no matter what, your projector is going to be 'due for replacement' in a few years, your screen can last through several projector upgrades if you buy a high quality one the first time.
i'm not sure i'd spend money for masking though. i'd buy a 2.35:1 format screen and if the bars on the side actually bothered me i'd use some curtains. but having a jvc x35, I can honestly say at this point in time I don't feel a need for masking in my room.
Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1130K, 7.1/5.1.2 audio
Sources: HTPC(Enby), PS3, XBOX360, Wii
Control: Harmony One