How much are you relying on the FM3 as a bass preamp for the tone, ditto for cabinet sim IRs? If the answer is "not at all", then have at it with running the FM3 into a traditional bass rig/combo. This is actually a very practical thing to do if you have a bass amp that you already like the sound of.
If, on the other hand, you're looking for the entire "modeling experience" complete with amp modeling and cabinet simulations, then bass is really no different, using a Full Range speaker system just as guitarists do - EXCEPT FOR - the amplification for bass instruments are more demanding in terms of the extended low end, and the clean headroom provided by the amp (depending on playing style/technique). This generally translates into needing better performing FR speaker system, thus more cost. Traditional bass rigs do "bass amp things" with a lot more ease than modelers doing bass amp simulation into a FR speaker system.
Also, factor in if you're using a fully modeled bass rig for performance on a loud stage and/or when your stage rig is needed to carry the bass sound into the audience. You'll not only need gear that can keep up with these demands, but also you'll need to train your ears and skill in setting the modeled tone so that it sounds reasonably good at gig volume and doesn't fall apart. This is different than low-volume tone creation at home or otherwise. That god-of-thunder tone you created by yourself at home might just go to crap once it's competing with a loud drummer and guitar(s), and again, not to mention that this assumes your full range speaker system doesn't give you the finger and deny you good sounding headroom in the heat of this stage battle. Thus, as correctly suggested above, hi-pass filtering and also compression/limiting start playing a key role in keeping things together.
For quieter gigs, coffee houses, etc., it's actually pretty sending fully modeled bass to a typical PA speaker and having it sound reasonably good. If that's you, then no worries really, IMHO.