Never seen those amps before, I wonder how they compare to the Micro VR and the B100R combos...
EDIT: Found this on Talkbass:
[quote]The 350 incorporates the Micro-VR's preamp and pairs it with a 350-watt class-D output section. The 500 borrows heavily from the 7Pro, but drops the tube, and adds some of the "tube emulation" from the Micro-VR.[/quote]