Yeah, I never really got the Coupling/Friends comparison personally. Perhaps I've not seen enough of the latter. Either way, I don't really buy it, but just passing it on!
As for Lead Balloon, the only similarity is that both lead characters are involved in comedy. One could argue that the whole characterisation (bitter, foot in mouth, irate, etc etc) is identical in LB to CYE, but as Jack's been doing that as his whole persona for the past decade or so, any such argument is automatic bollocks.