I have an M-2500, and agree that it's basically five settings, just like Jazz basses IMO. I like favoring the neck pickup slightly, so I like the M, but I'd be perfectly content with the L-2500's setup too. (I'd also love to have a passive mode.)
Another difference between L and M is that the M's pickups are always wired in series. It doesn't have the slightly mellower parallel option, let alone a single coil option like the available K-wiring on the L-series. So, while the M's pickups aren't as hot as the L's, they also can't be "thinned out" in a parallel mode. All such "thinning" is done via the blend and EQ.
Also, while the M's pickups might be "polite" relative to the L-series, they are still some of the hottest, baddest pickups around, with that characteristic MFD intensity that cuts through just about anything. I get plenty of thick, satisfying MFD punch out of the M, which can sound very aggressive through my G-K gear.