Do/have any of you used the barrel mount for these transducers, and if so, is interference a big problem vs a shaft mount? I've got a Terrova with a DIY shaft mount set up right now and I'm not happy with it. Id really like to go with the barrel mount so it's a bit more streamlined, but I'm concerned being right on the motor will wreak havoc, so I'd like to hear some feedback before I go out and purchase the mount.