My MK class:
MK-14 2 attachments, rapid fire, red dot
Skorpion akimbo (random)
Assault: UAV Sentry Airstrike (kind of random)
But yeah I have a fast trigger finger so rapid fire is useful for me. I think I cap out without it pretty easily. Red dot is necessary for me, I hate the iron sights. Kick isn't that useful imo. Still really easy to land precise shots without it.
I usually go with :
MK-14 - Holographic sight
MP9 - rds
Hardline (sometimes quickdraw)
claymore, motion sensor
I like the holographic site over the RDS because it has a little more zoom and I use the MK-14 on bigger maps with longer sightlines.
I don't use rapid fire because I don't think there is a need to. Not for me anyway. But I guess it could be useful on smaller maps and close quarters engagements.
I use kick. and it does make a difference. I usually double tap or sometimes triple tap the trigger and I've found that with kick the second and third shots are easier to land with kick.
Also lately I've been using a suppressor and holo sight. with the suppressor it seems to have a little less recoil.
MK14 + Attachment Proficiency + Rapid Fire + Silencer
The MK14 is Semi-Auto, avoiding CQB is probably best, since you'll most likely be outgunned by a guy spraying a full-auto MP7 in your face. The gun is great for medium to long range. I like using Blind Eye and Assassin so that I can stay hidden from killstreaks.
i love love love the mk-14.
personally i use it as a pseudo "sniper" rifle
i put stability on and either the acog or thermal. The stability at that point has so little barrel sway, it's awesome. In hardcore with the mk14 it's almost always a one shot kill. add slight of hand or scavanger/quick draw/marksman. akimbo some machine pistols and it's a nice load out.
You know. It's all about trial and error. If you don't have a fast trigger finger you won't really benefit from RF that much, but it does help in those situations where you need to get the extra bullet per second out, you know, those panic moments lol.
I usually run three set ups of the MK14.
Attachements; RDS, Silencer
Or breath, if you don't like kick. But, breath tends to hinder me so I don't like using it.
What I would do is try it with kick for a little while and then remove it for the same amount of time and see if theres a differences in your game.
I have tried it and noticed that depending on lag(at least for me) I can do better without kick the with. Just have to pay attention and make sure you fire more then one shot.