Well, I own a stock brand new 346, plus a 488 and 346 both Greffardized. The 346 is only a little faster than the 488, but is about 50% faster than the new 346. I think the 488 is a great saw, and the 1/2 lb weight difference is noticable. As well, I'm guessing it has more torque in stock form, considering the motor is a bit larger. It also turns a bit less rpm, is built very well. Most that have them report long life...it also has 2 rings versus the 346's one, perhaps that may equate to a bit longer life.
The stock 346 will remain unused till I have it built.