I use those on occasion and like them for what they are. If you leave it mounted, but remove the antenna for any length of time (ie, quick theft protection while in stores, etc), try to find a cap to cover the exposed connector for light rains, etc. Definitely remove the whole thing for the carwash.
You can also play around with an rf-choke if you like. Since the braid is now your ground, I played around with winding the coax into a small 2-inch diameter, 5 turn choke about 20 inches away from the mount. Minor improvement for VHF-hi , and also helps keep out common-mode noise going the other way into the antenna. Or you can wind several turns around a ferrite. Something to play with anyway...