Or are they too kite-able and easy to dodge?

Depends if you have a butt buddy. Me and a friend were doing zerker mystic last cbt. The bodies were flying. It was awesome.

Think zerker slayer would pair well?
& is zerker's SMASH(ts) a good opener in ganking?

Thunderstrike with speed glyph would be a good opener

Not really, Zerkers are really dependent on having a competent teammate with cc. To be blunt, Your not gonna catch anyone by yourself unless they are really dumb. Like not noticing you going red and sitting next to them charging your overhand dumb. Slayers wouldnt really pair with them well. If your buddy is going slayer i would recommend a ranged class to compliment. If you can get him to change so you can go zerker I would suggest him going either mystic, sorc, or archer. So really one of you has to pick a ranged class with cc. For duo groups its really a necessity imo. And imho mystic is the king of duo ganking. Of course really it doesnt matter all that much if your intelligent about it. Just having a good combo makes it much easier.

If you are the type that focus more on intelligence in your play, zerker can be fun.

If you are the type that focus more on reactionary reflexes, zerker won't be so fun.