Hi guys, thanks for all the feedback.
I do have web dominators already on the pack straps that won't get used often. However, I do use my compression straps pretty often throughout the day (loosen up when getting into the pack, then tighten up before moving) and web dominators are a bit more of a hassle when the strap length changes. I have used the elastic bands on other packs and they' slide easily enough when you're loosening or tightening up the load. I know Milspec Monkey sells the double-sided velcro that Mystery Ranch uses and may pick up a yard of those.
But these elastic bands-- surely they weren't created solely for tactical/military use? I would think some other industry uses them as well, so finding them locally at a home improvement store or something would be pretty painless-- but I guess not.
And nope, I'm definitely not shortening those straps. Lesson learned from earlier years.