I have owned this saw for over 16years, the same saw! Never changed brushes, or even tried to really clean it, I just blow it out with air hose at the end of each day. I have mainly used it for custom home building, all stick built homes, projects, and the like. This saw as never failed, during any project, I use the best 7.25 saw blades, I even use a 7.25 concrete blade to cut expansion joints in my sidewalks and other concrete projects, just blow out motor areas when done. I know at least 13000+ rafters have been cut with this saw, I always check the blade for 90deg off of the strong foot plate, has always maintained true to the factory 90deg setting. The saw cuts very easy, super easy one hand control,(sometimes two hands needed), I even cut long radius cuts in plywood/OSB never a slow down or bog from the motor. I also have cut LVL, PSL, and all other types of beams, never a problem. After the first two years, I replaced the cord with very nice 16ft long cord, makes it a lot easier to use around the job site, etc...
I also have other true worm-drives, but don't like them much, I let my crew use them, they can lug around the extra weight all day, and deal with hot motor areas!
Back when I bought this saw many other guys on the crew blew me crap, but I know everyone has replaced their saws, two of my buds have bought DW378 and now love them too! Over all this saw is a great design, the sky-hook works great, trigger handle grip, "T" handle solid, super easy blade changes, easy 90 to 50 degree changes and cut depth adjustments.
Only draw back I have ever notice, and had same problem with true worm drives, blade at 45deg, cutting beam ends, the blade starts to heat up and might get a little walk off of line and hear the motor start to bog, but never stops.
I bought another DW378 saw to replace my old, but it stays in my shop, I mainly use it for indoor light work, just so I don't have to retrain myself to know another saw. When the original saw goes out, I might even mount it on the wall like a trophy. or rebuild it, who knows!