Ollie, a dye rotor will mean he wont have to switch hoppers for every marker, if he upgrades his marker and ends up outshooting hit hopper he has spent £40 which he will only get £30 back when he could have just spent £50-60 in the first place and never had to change.
On top of this, both the rotor and the prophecy are some of the lowest profile loaders out there which hold a reasonable amount of paint, my prophecy goes all the way down the feedneck on my DM