I think it was a very hard call - it would have been interesting if it had been Tameka and Naga in the DO to compare their tangos side by side, as it were.
Perhaps what swung it for Laura in such a tight DO was that she was much more 'exposed' in her dance (and I don't just mean her costume!) but that she had to keep time while dancing on her own and use her body weight and core to help get herself in and out of lifts, which arguably are trickier skills for a non-dancer than being in hold. Or perhaps it was simply the judges being influenced by their perception of 'potential' (young, slim, reasonably fit - i.e. possessing a typical 'dancer's body') despite the fine words about judging the dance on the night.
I'm sorry to see Tameka go as I enjoyed her Charleston last week BUT I think she was always destined to be better at the 'character' dances than the straight (such as it is on SCD) ballroom/Latin and having done paso, Charleston and tango, they were coming to an end.
Incidentally I hadn't heard of either of them before Strictly, because I don't watch soaps or IACGMOOH, so I dispute Laura being a 'big name signing'. She has apparently generated a lot of Twitter traffic thanks to the Gio - Laura - Georgia 'love triangle' but that's hardly the same as being a big name beforehand.