I tested it at Capers today. Okay, so my max depth was only about 8m for 30 mins twice (teaching) but still.
The responsiveness was good, and the wireless device easy to work with gloves. The vibrations underwater can definitely be felt so you know what setting you're on.
I have the wireless device attached to my wing by a split ring, and carribiner.
The heat was definitely a whole new experience! I had a base layer underneath because even only on the first low setting, it's that's nice feeling of leaning on a radiator that's not too hot.
I didn't have it on constantly as I don't know how long the battery lasts as of yet, just on the surface to warm from the rain and at various points during the dive. Actually, it's worth it just for surface intervals!
I could definitely feel a difference - especially in my hands! I could actually feel the water that had warmed in my gloves, usually I hardly any feeling in my fingers at all.
I feel the cold very easily, so this has been a brilliant investment for me to actually enjoy being in colder waters! And this is after 2 short dives!
Also, on the Whites undersuit, I'd also recommend that (especially in combo with the Whites suit! - Ste @ M Developments: I read your thread on undersuit comparison and ended up buying the suit and undersuit!)
The batteries aren't bulky as soon as you get an undersuit over the top and they sit in a nice position that you don't even know they're there.
I didn't feel like the heat would cause burns, but I can see how that could happen with skin contact which is why I chose the base layer option.
I'd like to know how long it could last on each power, low is hot enough. I will probably test this out next time
