Omni-Wheels

[Addison4300]

So our team is new to using omni-wheels and before we order them we have a few questions as to what exactly we are buying, and what the best options are. We are buying 6 inch wheels from AndyMark but are open to other authorized vendors. We were wondering whether to go with the single omni-wheels or the double omni-wheels, and whether to go with plastic or aluminum. We understand that double omni-wheels provide a smoother motion, but how much smoother is it than single omni-wheels? If dual omni-wheels are significantly better, would it be worth it to buy aluminum double omni-wheels, or could we just buy 2 plastic omni-wheels and configure them like double ones? This option is less expensive, but is it less effective or more liable to fail? Sorry for the long post, we just want to cover all our bases.