well,
the Dice duke weighs 519 Grams,
the Rhyno Light weighs 565 Grams,
they are both roughly 30mm (but they are separated by almost a mm in width, so they are not the same rim)
The sun rhyno lite costs $105 each, while the Dice duke are only $72 each,
both have basically the same design and features,
However Dice claim the Duke as a Rough Trail riding Rim, while Sun Claim the Rhyno Lite as a Downhill and Dual Slalom Racing rim.
the Dice is no doubt plenty capable, but my money is on the rhyno lite,
I've used em myself, managed to flat spot and knock them out of true, but I never managed to physically bugger it totally.
The Rhyno is certainly well proven however, being specced on many dirt jump and budget downhillers from many brands.
One thing to consider,
if your going to use rim brakes, the Dice could be a easier alternative, as the rim already has machined walls, while the rhyno is painted/coated.. so if your using disks, the Dice might look out of place while the rhyno should fit in nicely.
Kind regards
Juls