This was a great post. Loved the amount of detail you put into.
IF THIS BIG WALL OF TEXT LOOKS TOO INTIMIDATING, JUST READ THE STUFF IN BOLD FOR THE TL; DR VERSION...
My solutions aren't nearly as in depth as yours lol however, I still believe them to be effective. Hasn't failed me yet. Keep in my, I like to camp 60% of the time so my whole approach to it was different.
-my primary tactic is explosives! When they combat roll, they don't move to far out a certain radius, especially since they roll left to right more often than in one repeated direction. When they do this, you keep calm, take your RPG or grenade launcher and launch it at them (beside to aim it at the ground around them. If you aim it up in the air, it has a higher chance of missing. You don't need a direct hit, just the splash damage)
-to add on to that explosives tactic, if you happen to be behind a corner and they run out in the open, a well placed sticky bomb works wonders! This by far is my favorite and has served me the most ever since I had this one used on me.
-Free aim strafing with the combat MG is a decent tactic. With 200 rounds on the extended clip, you shouldn't get caught reloading out in the open (hate when that happens). Whether it's you or him, SOMEBODY is gonna die before you shoot 200 rounds
-miniguns are risky, but effective. Since they are free aim weapons, you can let the guy roll all day! Lol. They have no reload, and deliver devastating damage quickly, so it's a perfect solution if you have a steady hand and can steady your aim before he lands enough shots. Just be sure to still strafe.
-the shotgun has already been mentioned, and does have a powerful spread, but at times I use the AP pistol.
"The AP what?" Yes, the AP pistol. It's a pistol so it's handling is quick and easy, and in my experience you can better target someone in between rolls. It's pretty accurate in close range. It doesn't do heavy damage, but if your precise you can land a headshot fairly quickly.
-If your are caught out in the open, (which I try not to be.) and the guy is spamming the combat roll, the best thing really is to watch him move and feel it out, even if it costs you a kill or two (be patient). Most players repeat the same pattern over and over again. So after you got his game, you can consistently lock and release your aim right along with the timing of his rolls, getting in shots until he's dead. Sometimes players are predictable to the point where I headshot them as they go down for the roll... And never get back up lol. You just gotta roll with the punches as they say.
-last but not least, combat roll right with him! If he can do it, so can you. Roll with him until he pauses, and then roll some more, shooting the whole time. This is meant to be more taunting than anything else, so be wise lol.
These are all things that have worked for me at one time or another, so feel free to try then and do what suits you best.
Disclaimer: the effectiveness of any of these is always dependent on the skill of whoever tries them.
^ That's also damned good advice... o.O