I agree with elpopp!
I sell and have used the Mystic gloves and the thicker gloves have a tendency to fatigue after 10-20 minutes of riding, making it hard to hang on.
West brings up some very sage points that should be taken very seriously. But I find that I need warmer gloves when it's in the 40s as well as, I know a lot of people who's hands get cold really easily and need something really warm on them, even at 60 degrees! So for people needing something warmer, the NP 3 finger 5mm Mitts are an excellent choice!
I can kite in the NP 5mm mitts for 2 hours without my hands & forearms screaming for relief, as well as... they are warm! They have a curved grip, are very soft... and don't even seem like they are 5mm thick. I have sold MANY to local guys around here and they all love and swear by 'em! The only complaint is they tear with hard-core use. They are made of a very lightweight, air-infused closed cell neoprene. Being lightweight and air injected is really what lends themselves to not tiring your hands & arms while gripping the bar. The air inside the neoprene also acts as an insulator for warmth. The closed cell rubber blocks the wind which adds to the toastiness factor. But all this together makes it a glove you don't want to abuse. If you overstretch the glove when pulling it off, the neoprene might get a little slit in it. If it gets pinched or if you run it across something sharp, it might cut the material. However, as with any smoothskin, wind blocking material... if you repair it right away with a little AquaSeal, this will prevent the slits & cuts from growing and turning in to larger tears in short order, allowing longer glove life!
If you're a real hardcore rider, invoking lots of friction on these gloves, they will wear faster than standard, open cell neoprene. But the warmth & lack of fatigue factor are far worth the tradeoff. You'll just be buying replacements after a while. These gloves also feature NP's Bamboo Charcoal inside lining. This material not only resists bacterial growth so you don't get that mildew stank after a while, but also makes them easier to slide off your hands when wet. This helps prevent over stretching upon removal.
I keep these gloves in stock, in every size, all the time. Below is the link to the gloves in my eBay store but if you contact me, glad to have you in to the shop or possibly even bring them to the beach next time we're all together kiting! I also carry the AquaSeal to keep your smoothskin rubber maintained.http://www.ebay.com/itm/2016-NP-GBL-3-Finger-5mm-Kiteboarding-Kitesurfing-Glove-/251939828434?
I really like these NP gloves for days too cold for no gloves but not quite cold enough for 5mm; http://www.ebay.com/itm/2016-NP-GBL-1-5mm-Kiteboarding-Kitesurfing-Glove-/251994554321