Some of you are probably already bored from me saying that an add-on is conflicting, so I'll throw this here. I have no clue what type of addon this can conflict with. However, I can say some of the most popular:

ArcCW - works fine
CW 2.0 - Works fine, but the acog on CW 2.0 gets broken, but who uses the stock acog lmao
TFA - Works fine
FAS 2.0 - Works fine
M9K - You use this?
Simfphys - Works fine
Any gamemode like DarkRP or TTT - Conflicts will probably happen if any server installs some sort of 50gb mod mostly consisting of LUAs
Maps like bigcity or fork - why would it?
Life Mod - Maybe it will, I won't bother to try it so just be warned
Portal Gun - Might conflict with something, not really sure
Minecraft - All fine and dandy
Climb swep, or wallrun and mantling - Not related at all, so no. In fact, it looks very good with these!
Wiremod, or any tool mods - No conflicts? Unless there's an addon that specifically replaces stuff on weapons, like a muzzle replacer, or realistic bullet physics (even with CW 1.0 already has that)

With that out of the way, why would any mods conflict? I have no clue. I'm just familiar with simple coding, so I can't honestly tell you. That's all. Go on, do something else.