I use the viking system with the locking rings. To be honest, I don't know why I chose the viking system over the SI Tech version when I bought them. Something sold me on the viking system but I don't remember what. It might have been that the guy here on SB that sells them lives 45 minutes from my house. I was able to go pick them up at his house and he was selling them for a good price. Either way, they are easy to put together and use. I use the blue smurf gloves with the liner. The vikings do not require you to twist the rings very far to lock them in. In fact, others have said that if you really crank down on them, you will have a hard time getting them apart after a dive. I line up the tabs, and tighten them about 1/2 inch. I've never had problems getting them on or off without help. As long as you get everything put together fairly straight, they will be easy to use. If your rings are installed crooked, they probably wouldn't line up very well. The good news if you mess up putting them together, you just take it apart and start over. I made small adjustments to mine the first few times. Now I have them "dialed in" so they work great.
I've never had a leak. I don't go crazy checking the o-rings but I also don't throw the gloves in the bottom of my bag to get covered in sand and dirt. The gloves get rinse with all my other gear after a dive. My wrist seals would still stop water from getting in my suit if I had a leak, except for the fact that I put a piece of tubing in my seal so my gloves can equalize.
When I first got the gloves, I had a "blond moment" where I had the smurf gloves go into the inside of the ring and the fold outwards. This allowed the inside of the blue glove to come in contact with the water. I don't know why it never occurred to me that this would cause the gloves to leak...bad. Luckily I used them in the pool first and knew something was wrong when my gloves were full of water. Good news is my wrist seals were verified to work because my suit was dry (I didn't put the tubing in). I got out of the pool and looked at the gloves and the it suddenly hit me...A) I'm an idiot B) the gloves need the go on the outside of the ring and fold into the inside. This keeps the waterproof part of the glove in contact with the water. Once I fixed it, I wondered why I didn't think of it the first time. I guess it was the blond hair...Anyway, now they work great with no leaks.
A lot of people here wear wet gloves. My hands get cold easily and frankly, I don't like having anything on me be cold--call me a wuss. The only negative to the blue smurf gloves with liners is you have to get used to having that much material around your hand. It's kinda like wearing ski gloves...you can't pick up a needle wearing them.