I have the Deus underwater kit and the antenna does have to be very close to the remote for it to work. I tuck the antenna wire behind the arm strap in the waterproof remote pouch. I've had times where things get really quiet and I realize the antenna has fallen out from behind the remote. Like vferrari said, I don't trust that XP remote pouch though! My water hunting is typically waist to chest deep, so really it protects it from splash and quick dips under. The main reason I bought the XP waterproof kit, over making my own, was another member on here had one and the remote pouch failed while under water and trashed his remote. XP replaced the remote and pouch under warranty. So my decision to buy XP's $60 underwater kit, was really a cheap insurance policy to protect me in case of a failure. If I had the remote underwater in an Aryca case (which is MUCH better made than XPs) and it failed on me, I am sure it would void the warranty on that expensive remote.
I hunt in the water a few times a year. I hunt on land 99% of the time. If those percentages sway and I am in the water a dozen or more times a year, I will buy a water machine. I feel like using the Deus as a water machine is suitable for someone who primarily land hunts, but maybe wants to hunt the water every now and then. Dealing with antenna wires and headphone wires when using the Deus in the water is acceptable when done infrequently. But if I was going to primarily hunt the water, I wouldn't pick the Deus as my machine of choice. I am actually trying water hunting more this year with my Deus, and if I like it a lot, I will probably buy one of the Garrett AT machines this fall as my water machine for next year. I obviously prefer the Deus, but it would be nice to have a machine that is truly made to be tossed into a river right out of the box!