i own the novak ss system, and couldn't be much happier with it. fast/powerful/yadda yadda, but best of all NO MAINTENANCE.
to build on what previous people have said, i primarily do not run mod due to the increased maintenance/cost typically associated with it. while claims of improved long-term performance from motors like the v2 make me revisit the subject, those that have seen prototype versions of novak's 'unlimited', will probably agree that thing is going to be AWESOME. i've only seen it run at socal rc, but it appears to have the torque/speed of any motor out there.
i do hope some features are built into it though such as drag brake point/value, etc. having to set the neutral 1/4 of the way into reverse to get off power braking makes for a lot of dead trigger space.