My experience:
1) Buy casters/rollers not by type, but by rated load. Buy casters with a rated load at least 4x the total weight of the cab. When the rollers hit a bump or divot, the actual impact is many times that of a normal load.
Example: if the cab weighs 100 pounds and you have four rollers, 25-pound or 50-pound load rated rollers will self-destruct quickly - probably the first time you hit a hole. Buy rollers rated for at least a 200-pound load.
2) Removable rollers are kind of a waste of money. Buy them, secure them well (I usually use 1" long #10 machine screws) and don't worry about them. If the cab is a square cab and you are worried about it, tip it on one side and play it.
Here are good NON-removable casters, the only kind I use. 255 pound rated load, $20 each and worth it. Install, roll the cab into place, lock the casters and play.
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If you absolutely, positively gotta have removable ones, then buy hell for stout. It's worth it to only pay ONCE.