i dont know but i would think the 2nd tier was more to look for obvious problems that crop up. like the sagi that was spotted almost straight away on release. and to check for editing errors etc. not run a full playtest as hopefully thats what we have got right with balance etc and maybe only missed one or 2 due to seeing constant updates.
to quote what matt said in that post burger linked so wouldnt say a full out playtest, more an attempt to break things.
A little while before release, we are going to have a second group created, drawn again from people on this forum (probably the mosy vocal, cynical and pessimistic ones ). This will act as the Test Group for 2e, using the final laid out files for the game, and will have the opportunity to poke holes and break balance.
to quote what matt said in that post burger linked so wouldnt say a full out playtest, more an attempt to break things.