'"So, you were at the pub last night, yeah?" is far friendlier than "So, you were at the pub last night, eh?", especially when you say the latter with the hint of a cynical snarl...' When I imagine these in an English context and in English accents, I understand exactly what you mean. In Canada, however, someone saying, "So, you were at the pub last night, eh?" would be ordinary speech, and would likely either be a neutral conversation-starter ("Many people there?"), or full of bonhomie ("Betcha had a good time, eh?"). Of course, if it were a cop saying it while he's got your face shoved against the wall, it might not be so friendly.

'"So, you were at the pub last night, yeah?"' would just sound kinda weird.