I don't recommend Mercedes. I do maintain that they are the same franchise that won the 2009 WDC and WCC. There has been enough continuity for that to be a reasonable statement, in my opinion. How they won it (a controversial rule interpretation) is completely beside the point as far as my point is concerned.
What is NOT beside the point is that Brawn has spent the last 3 seasons languishing in a distant 4th in the championship so it doesn't really matter who they are or how much continuity there is - you're as good as your last result - and Mercedes don't have much to feel pleased about since - well - Brawn. The worst McLaren has done in the same time is 3rd - and that year, Lewis' fans were screaming blue murder at McLaren for not providing him the car they thought he deserved.
Let's keep this on topic - not Brawn, not McL - but Lewis; your argument (correct me if I'm wrong) appears to be that he is clever to be moving to Mercedes because in 2009 they won the WDC and CC under the name of "Brawn" (ignoring the more immediate and telling lacklustre past 3 years). You appear to think that he is better off without McLaren even though they consistently finish 2nd in the CC and give him a shot at the WDC most years.
I get it, if you admit that championships are likely a long way away for Lewis now (not taking this year into consideration) and think that's OK due to the reduced expectations on him and the reduced pressure. What I think you may be failing to take into consideration is that there will be CONSIDERABLE pressure and expectation from within the team. Given what he is costing Mercedes, they will want him to perform. He escapes the pressure cooker of a competitive team to take on the more arduous task (from the perspective of dealing with the team) of the pressure cooker of a less competitive team.