Hey huser,
I don't think it is much of an issue. The front brake is easily sorted by buying a second hand off road master cylinder and caliper, then just switch over. I have a complete set in my garage so I can just chuck the off road brake on if I want to. Then you just make sure you buy a set of off road wheels with brake disks.
As for the suspension SM does go off road and do pretty hefty jumps and whoops and other stuff. You're never going to win an MX championship but you'll certainly be able to ride fairly well. You can adjust the SM suspenders to work better on the dirt too. I it becomes a limiting factor then there's plenty of used stuff out there at reasonable prices.
Hope this helps,
Simon