I highly recommend Sound Anchors. Bob made a stand for me with wheels when I had a Levinson 333 amp, a beast. It glided easily across my wood floor and improved bass performance as well. The casters were high quality and worked smoothly.
I now have a pair of stands he made for my VTL double deck amps, even heavier than the ML 333. I chose spikes this time. With the spikes sitting on Sound Anchors Conecoasters, I am able to slide the amps on the wood floor without damaging the wood and have better coupling to the floor. If your floor is tile, this may be a problem because of the joints between the tiles and you should probably stick with wheels. Obviously, carpet would also suggest wheels.
I now have a pair of stands he made for my VTL double deck amps, even heavier than the ML 333. I chose spikes this time. With the spikes sitting on Sound Anchors Conecoasters, I am able to slide the amps on the wood floor without damaging the wood and have better coupling to the floor. If your floor is tile, this may be a problem because of the joints between the tiles and you should probably stick with wheels. Obviously, carpet would also suggest wheels.