Just installed this mount on my kayak yesterday and have been pretty impressed so far.

The amount of arm deflection I see with the bigger GT54 transducer is a little concerning, has anyone had any issues with that or come up with a remedy?

I have the same Garmin 93SV and the GT54 mounted on a Pelican Catch Pwr 100. https://pelicansport.com/products/kayak-catch-pwr100-mfp10p300

I use this (https://www.yakattack.us/cellblok-clb-1002/) to hold my battery, and then I slip it into the side tacklebox holder area on the same side that I have the transducer mounted. I wrap all of the excess transducer cable on to that cable wrap you see on the back.

I use this as the transducer mount: https://www.yakattack.us/switchblade-transducer-deployment-arm-ffp-1001/ . All of the joints lock down nice and tight, and the transducer stays stable in position very well for me. I assume that's what you meant by "arm deflection". I have to move the arms into position once I get to the water, but it stays in position once deployed. I have tightened the screws once after a long trip where I moved the transducer a lot while learning some things, so that's probably something I'll have to keep an eye on to make sure the arms have the right amount of friction to allow folding but still hold when deployed.

And then I have my actual Garmin unit mounted on the battery cover lid of the Catch Pwr 100 (so, middle of the boat in front of me). It's a short run from the battery box to the Garmin, and I just let the cables run along that side of the boat. No slack or anything, never had an issue with it getting in the way.

I don't feel any significant weight imbalance with this setup. I have my paddle holder, most of my tackle boxes, my anchor pole, and a few other things stored on the opposite side of the transducer/battery setup, so that helps keep things even.

I like your electrical tape idea! I stopped using zip ties and am currently using waxed lacing tape to secure cables, but I think I'll try electrical tape next.

Very nice, I like that arm setup as well! I took my setup out yesterday for a test drive and really didn't see any deflection in it as I paddled, so far so good.

I will need to come up with a way to really tie down that transducer while transporting the kayak, I don't want it slapping around or wearing that arm.

For transport, I take my transducer setup off of the Scotty mount (one nut), unscrew the power and sonar cables from the brain, and then put the battery box, the transducer + arm (folded at 2 joints to make it small), and the brain (with the screen cover) into a Sterilite 25 qt latching box from Home Depot.