VRS happens when you descend through your own downwash too quickly, and the blades start recycling a revolving donut of air. I don't see why it would be a problem for this thing in low speed hover any more than any other rotorcraft.
Here's what you need for your craft to qualify as an ultralight for those interested. The above information is incorrect although it's close!
edit: wow can't believe I forgot this in my original post! there's no speed limit for ultralight rotorcraft due to the unique power curve (they need more power than it takes to exceed 55 knots in level flight just to take off / hover)
Yes, really, that is the FAA's official position on the matter and that's pretty awesome.
(a) Is used or intended to be used for manned operation in the air by a single occupant;
(b) Is used or intended to be used for recreation or sport purposes only;
(c) Does not have any U.S. or foreign airworthiness certificate; and
(d) If unpowered, weighs less than 155 pounds; or
(e) If powered:
(1) Weighs less than 254 pounds empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation;
(2) Has a fuel capacity not exceeding 5 U.S. gallons;
(3) Is not capable of more than 55 knots calibrated airspeed at full power in level flight; and
(4) Has a power-off stall speed which does not exceed 24 knots calibrated airspeed.