I replaced all my Bogner cab castors with 3" Mesa castors. They are so much better than those other POS castors that Bogner and others use. Plus, I think they have better tone
For me, when I remove the casters I've found it's not an issue of acquiring more bass as much as it is thicker bass.
I don't experience and "woofy" lowend, but I also use a decent amount of mids and presence/treble so that slices through the bass and keeps it pretty well defined. I also tune to standard drop D so my guitars are not really far in that low register.