Just made a control shaman deck that included 2x echo murloc 2x Mr. infinity murloc and 2x slurp. Great for early game control and mid game WTF moments, many of the games are straight up no contest... especially when they realize it's not a murloc deck.
I think its a solid variant. I run a Portal Demon version of control shaman which is also about six cards. Not shure if the murloc variant is consistent enough but i can do woderful things and be a fun surprise.
I am not expert at Control decks, but the Echo Murloc is only good after Hagatha. Out of that, and out of solid Murloc synergy, it's a bad Tempo loss, and hardly threatening enough for Control mirror or Midrange.
And the Fisherguy is only good in combo or on curve at best. Dead card in any other case.
Surely their shenanigans are juicy, but how often do they happen? How consistent are they?
Overall,I'd keep them only with some more Murlocs, for consistency (the fake Murloc deck is definitely a great move). 8x instead of just 6x.
To me, the only safe card there is the Sludge Slurper: the guy's just good in any phase of the game, even on its own.
I like the combination of control and some murlocs or tokens. Most people don't expect it. I recently made a control/big shaman with some very sticky minions and two Soul of the Murloc. At some point my opponents usually expect me to play big stuff and then you can really surprise them with a wide board and finish with Bloodlust. I climbed quite a bit with the deck.