Don't forget the Falklands has to be provided for out of those 66, plus a couple of career posts (Sqn Boss, 2ic) plus standards, then factor in the constant throughput to SH that is supposed to be the remit of the SAR Force and you have more like a third of the present Mil SARF to be employed front - line. The MoD is supposed to pay 70% of the bill for SARH but only have 30% or so of the front line as Mil - maybe that is why it might get shelved.
I don't think that there will actually be that many that do want to step sideways especially since some who jumped early expecting preferential treatment regarding postings have discovered that seniority in the company is what dictates where you get to go. Anyone leaving the mil would generally want to stay where they are but if it is a nice location they will probably be seen off by those who have been in the company for a while.