How does the 17hm2 barrel shoot?
To the OP, if the Quad fits, and you feel comfortable not having an action for all of your barrels, and you can get used to resighting for different barrels, go for the Quad. If not, then don't.
Will someone else be likely to join you? Will an extra gun be more useful than the extra space, meaning grab case number 2 and open it, as compared to grad allen wrench, release barrel, install new barrel, tighten allen wrench, reload magazine or change magazines, rezero scope with chart or shooting.