Choose the model which uses the TI 0.66" DLP660TE chip. Di hamak mas mataas native resolution ng DMD nito at 2k tapos 2x cya magoutput ng image making an effective 8.3M pixels per frame. Ung sa epson kasi na pixel-shift 1080p x2 lang kaya 2k effective resolution.
Those models that used the TI 0.66" DLP660TE chip when observed side-by-side against the Sony true 4k PJ, same lang din ung details when viewed closely at 12". therefore effective ung 4k rendering nya.
Regarding the dust accumulation, try to check AVSforums DIY paint screen "Silverfire", may halong satin-finish kasi un kaya pwede mo punasan with wet chamois automotive cloth ung screen, I dont see paint residues dun sa basahan after ko banlawan. Masasabi ko hindi natatangal ung paint.