I'm a Mapul MMS fan (
http://store.magpul.com/category/51) , although my Troy is nice too. Here are some things to consider.
1. Thick webbing or padding is always preferred. The Troy is padded nicely.
2. Attachment mechanism. I prefer the QD mechanisms or clips. I'm not a fan of threading the webbing through slots on the rifle. Too hard to remove quickly if required. YMMV.
3. Shock cord is nice, but I don't find it necessary. While it seems to slow the impulse of the firearm dropping down, I find it doesn't settle as quickly. YMMV.
4. Like a single solid QD for emergency exit or reconfiguration. I find that having multiple buckles, etc just gets in the way and makes the sling "ridged." For example, on that Cobra (just of illustration, I'm not picking on it) you notice it has two buckles in the loop that goes around you. IMHO, their too high (I want them at the triangle piece) and I only want 1. Also, the QD buckle between the triangle and the clip isn't needed or wanted (for me). It's just something that will make noise by banging around. YMMV.
5. Choose your mount locations wisely so as to allow shooting from either side of your body. A QD on one side may work fine (e.g. Magpul UBR), but it also may not. Also, go for the lightest and least complicated system (e.g. I use the QDs on ARs with rails that have them built in vice adding my own on the rails to get a bit more customization).
Remember, that a one point sling serves two primary purposes:
1. Weapon control for CBQ engagements where the threat is inside your work space.
2. Weapon retention when you need to use another tool (e.g. handgun) or otherwise must drop/release the firearm.
Finally, please, please only intentionally release the firearm (e.g. transitioning to the handgun) when the safety is on. Otherwise, the swinging rifle may catch the trigger and discharge into your leg/foot. If you ever get a chance to see pictures of what happens when you don't, you won't forget! FYI, you'll likely loose the leg.
