I use glass when I'm doing neg composites but other than that i'm glassless. I always focus on the important part of my image then if theirs any random in and out of focus for the rest of the image I'm not bothered. the only time it's an issue if the neg pops during long exposure times. For that situation I'll use glass. Also I am in the habit of taping my negs flat to the carrier. Once I do create a neg glass composite. cleaned and sealed it never is taken apart so I only have to do it once. It's then filed in an envelope and stored in a wooden drawer.
Glassless for both my 23C II and MXT 4x5 - already have multiple formats for each (35mm - 6x9 for the 23 and 35mm - 4x5 for the45).
I have wondered if glass would help when attempting to print image at the end of a strip (have you ever noticed if you trim to close, that is the one you want to print? or is that just my dumb luck)