Thanks Tom. The biggest issue I have with them are that they are very heavy. Maybe 400 lbs. Not too big a deal on a flat smooth surface, but I like to keep they in front of a south facing white barn door in the winter. So that is located up the driveway at about a 20 degree incline. So I try not to move them too much. One year I had an avocado tree in one of them. The forecast low was going to be in the teens and it was in the 60's that day. It was Super Bowl Sunday so I thought I had plenty of time to move it after the game at about 9pm. When I went outside after the game it was 22 degree. Needless to say, but the avocado eventually died from that event. I guess that would be true of an cold sensitive container plant.
The other issue with the heaviness is that my garage has a 3/4" lip on it, and each caster has to be somewhat lifted up on to the lip. Momentum sometime works to get the caster up, but one time the caster broke away when I did that. So if you have a big lip like that, you may want to consider a larger caster.
If I need a ladder to pick my fruit, I'll consider that a good problem to have. Van