If you can retrieve your cartridges from the processer, it makes
sense to roll your own. I carefully clean each cartridge (especially
the trap) just before loading (using a large-bulb hand blower to blow
out dust - the same blower is useful during the loading process).
I use Kodak reloadable cartridges, and loaders that have open traps
(the film does not pass through a brush or felt trap). I get fewer
scratches with my reloads than I do with preloaded rolls (at least
after the first run of film through a set of cartridges which reveals
the ones that scratch - thereafter, the cartridges last indefinitely,
especially if you do not store film in them for long periods with the
tongues sticking out [that spoils the light-tightness of the traps]).
It especially makes sense to load your own film if you do your own
processing, and if you do a lot of shooting. You can also make
custom length rolls. (I prefer 35 exposure rolls, so a roll just
fits on an 8x10 contact sheet.) Hope this helps.