Glad I could help, obscura.
So, I was thinking about the sidemount vs. full mount in terms of MMA application, because I've never really favored the full mount.
There's a typical belief among the BJJ guys that I train with that the mount, the backmount and the back positions are superior in competition, combat and MMA because they give you alot of leverage and your opponent has basically none. As true as that is, there's a big price for taking the mount.
When you are in the mount, your just there. You can't move or be versatile. Granted, there are plenty of ways to attack your opponent, but all of those attacks start from that same position and, if your opponent is smart, he's going to make it very difficult to get out of that position if you want to do something else.
I have no problem with being in full mount. Pounding a guy's face into hamburger meat is definitely an effective way to win a fight, but it's not the most fun or the most efficient way and mound isn't always the best road to it.
When you are in side control, you're opponent has the ability to sneak out if you make a mistake, but because of the way that your center of gravity is just hanging out, it's pretty difficult for them to do a handful of things, like grab the legs (the classic wrestling and jiu-jitsu sweep) or buck (assuming that you are in a stable side mount, belly-to-belly or lounge position.
The attacks from side mount are the same, and you can set up all of the moves that you can use in mount, like the under the head americana (slip one arm under your opponents head as you lock down the arm for the americana, and pass to mount to improve your leverage, but you don't even have to mount to finish), the Fedor style kimura from side control (he tends to isolate the arm, and if you can pull that off then the position is that much better) and my favorite choke (the ezequiel choke, which is another "slip your hand under the head and pass to mount to finish" move).
The sidemount also offers you the opportunity to do something that you can't do in full mount without losing leverage, which is smear your opponents face with your chest. As a hairy chested dude, there are some psychological advantages along to the pressure on my opponent, but it also gives me the opportunity to set up cool techniques like a north-south choke, which most people don't think about because they are always so focused on going to mount.
A good sidemount is as much about speed and pressure as a good scramble, and it's also about being able to make your opponent make mistakes. In mount, there's only a few (though common) mistakes that your opponent can make. They can give up their arms or their back (or their neck, in gi grappling). In sidemount, you have the power to transition quicker to different, creative positions that allow you to attack your opponent in different ways. For example:
If my opponent is protecting their arms and I'm not allowed to elbow them in the face (say this is a grappling match, or an MMA match where I don't want to risk losing a controlling arm by using the elbow), I can smear my opponents face and move to north-south or I can go to a reverse mount (so my body is facing the legs), insert a knee into what I call a reverse-half-guard position and go for a knee bar, toe-hold or roll back into a heel-hook or, if I want to go wrestling style, I can scoop under my opponents leg, go under the head, and roll them up so I can force backmount, mount or a hammer lock position (that's the setup position for the armbar from mount, for those who aren't familiar with Ken Shamrock's submission grappling terms).
Personally, sidemount gives me alot of options with my submissions and my positions, as well as allowing me to attack my opponent in ways that most guys don't train for. I feel like that gives me an edge that a position like mount, which is static, as painful as if might be to be stuck in, doesn't.
Hope that was helpful for guys trying to find a comfortable spot on the ground. Remember, sidecontrol and be static and slow, but when it's played right it's the fastest and most aggressive transition position for a grappling offensive.
Sig by Toxic
Barnett - Toquinho -Werdum - "Nurmie"
Z. Gurgel - Morango - Rocha - Tiequan