I have owned a K380 for a while now and just bought a K400 with a remanufactured motor from Home Depot for about 130.00 off regular price. I have noticed that the K380 runs a lot faster then the 400 is that normal? Which setup is better overall? I do like the built in dolly on the 400 but the 300 seems to have more punch to it...any help is appreciated. Should i return the 400?