Hi Jaymar
I have the Jet 60A, which spins at 5500rpm I think. The motor is 1.5 hp.
I am not claiming any particular knowledge here at all, (so I hope others will chip in too), but I'd have thought "chatter" was less do to with speed and more to do with power, blade sharpness, outfeed table setup, or blade adjustment.
If you're planing tough hardwoods, I imagine a lower powered machine may struggle to cut cleanly, compared to a higher powered machine - assuming both are using very sharp blades.
It's possible technique may be contributing too. Are you making smooth continuous-pressured passes through the machine?
Cheers
Aragorn