No hose (except on my CCRs). No SPG. Never disconnect any of my transmitters.
I have used AI transmitters on every dive since I started in 2014. I also used an SPG briefly, when I did my initial tech training and my instructor required it. After class, took the SPG off and left only the SPG.
So, around 800 dives now with AI transmitters.
I've never had one get damaged. Never had anybody grab one and try to use it as a handle.
Adding a HP hose, instead of screwing it directly into the 1st stage adds several failure points that are just plain unnecessary. Extra O-rings, and the hose itself. And, those additional failure points are all ones that, if they do fail, you'll be losing gas. With the transmitter screwed directly into the 1st stage, there is only 1 O-ring. If it fails, you'll be losing gas, but it is a static O-ring. The time I've seen one fail is when the transmitter got a little loose and gradually started to unscrew itself. When it gets loose enough and you turn on the gas, then the O-ring pops and you start losing gas. Fortunately, that failure is generally only going to happen when you turn the tank on. Once on, if it doesn't pop, then it is EXTREMELY unlikely to pop later, after you are in the water.
In short, no HP hose makes you MUCH less likely to have a failure in the water that causes you to start losing gas. On the plus side, when a HP hose or spool O-ring does go, the gas loss is generally pretty slow. You lose gas a LOT more quickly if a LP hose (i.e. one of your reg hoses) blows.
I have:
Single tank reg set with 1 transmitter (on diver's left, and I mount the 1st stage canted a bit, so the transmitter is angled down some to make it stick out less and look less like a handle).
Doubles regs with 1 transmitter (on left post reg, pointed down, where it is protected and where an SPG would go, if my transmitter died and I needed to change quickly).
Sidemount regs witih 1 transmitter on each 1st stage (1st stages mount to takes so the transmitters are pointing down and protected).
rEvo CCR with 2 transmitters, one each for oxygen and diluent. These are on HP hoses. The way the regs are on the CCR make it where there is not room for the transmitters to be screwed directly into the 1st stages.
Optima CM CCR with 1 transmitter, on the oxygen. That one is also on a short HP hose. Same basic reason as the rEvo. No room for it where the O2 reg attaches to the cylinder. And, really, maybe it COULD fit there. But, on that unit that would mean the transmitter would really be sticking out and vulnerable to getting smashed on something during a dive.
That is 7 transmitters, plus I have one spare, ready to go in case one dies.
I don't let boat crew or shop staff handle pretty much any of my gear and definitely not my regs or computers. I have occasionally let them keep my back plate and wing overnight and bring it to the boat for me the next day. When my regs come off my tanks, they go in a pretty normal reg bag. No special padding or precautions to protect my transmitters.
None of them have ever gotten damaged. None have ever died and made me lose any portion of a dive. I have had them die once or twice where it just needed a new battery, but I have always caught that well before time to splash, when changing a battery was no problem. I did have one die when I replaced the battery. That was a known issue and Shearwater replaced it immediately, at no cost to me. I had another transmitter in my bag, so I just swapped that in and then went diving.
I used to use button gauges on my 1st stages where I also had a transmitter. I don't use button gauges for that anymore. One reason for getting rid of the button gauges is that it forces me to dig out my computer and turn it on to verify my tank pressure when I put my rig together before a dive. That means that I don't forget my computer (I have almost left it in the truck once or twice when heading out on a boat), and I confirm that the transmitter and computer are both working. With button gauges, it might happen that I would assemble my rig, turn on the gas, check the button gauge to confirm the tank(s) were full, and then carry on without having my computer or knowing whether it and the transmitter were working.