I just purchased an SQ-480 and used it to mow a 2 acre field. Snapped the **** shear pin right before I finished. and finding a new shear pin at the dealer has been fun, It's a 1/2"X3" bolt, and they were out, This was after he eliminated about 10 different possibilities for the shear pin my pto shaft used. Pain in the butt. I have actually heard of guys putting a 1/2"x3" grade 5 bolt in there in place of the standard shear pin. They must be rich to be able to destroy gear boxes every time they hit a stump or other obsticle.....
anyway, the SQ- series is a little on the light weight side of things but for the money it isn't a bad deal. I would have preferred the clutch, but that was more $$$. Mine actually cost me $850 (don't laugh I live in NJ) and that was the best price I could find, heck even tractor supply was that much for less of a mower. anyway if you can afford a larger, more substantial mower than the SQ series I would get it. You may find that the initial price break is overridden by the overall down-time, repairs, and life expectancy of the mower...