I have a similar setup to Phil’s and have been very happy with it. I would highly recommend it since your can fold down the antenna for your garage or car wash etc.
My experience wheeling with the antenna down has been fine. Generally, during wheeling you are in close groups and can send and receive well with the antenna down. (assuming your have a good setup with low SWR)
I had an interesting "accident" and the MI Snow Run with mine. I had the antenna up most of the run do to lack of big branches with low clearance. However, going down a killer hill I was watching the hill and not the tree I was going under. It snapped off the antenna just below the folder over point on the bracket shearing the metal in half. Surprisingly it did nothing to the mount just the fold over bracket.
I am now going to mount my Wilson 1000 whip on top as a replacement. I want to add my Texas Star 667 to my setup so I can handle the additional power and so I can "reach out" to the front and rear of the lines. (and other states)
-Acheron