We used pneumatically-shifting octocanum for several years. It's big, it's clunky, it's heavy, it's expensive.
It also made for some awesome omnidirectional awesomeness and some fantastic defense (and plowing through defense--we often had no issues even against treads and six-CIM tank drives). My drivers *loved* it, and it's about two lines of code harder to program than octocanum in general.
So it's definitely a trade-off.
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We made everything ourselves. Our wheel pods were 3/32 steel plates, plasma cut and then bent in-house.
https://www.youtube.com/watch?v=FqQ65JyNBfg
https://www.youtube.com/watch?v=ouoV9nP_LKE