I have one.
I recently got the 5150 III 50w that everyone raves about. It's nice but I like the Peavey RockMaster more for some things.
It's more brutal, thicker and has active EQ controls, can be very flexible. Both drive channels have silly amounts of gain available. And the clean is actually nice.
The 5153 "screams" and you can hear a bit of the modded Marshall / Soldano DNA in it and the RockMaster sound is more of a "throaty grunt" and not as refined.
If that makes sense.