What about also the fact that HK will probably catch up with the rest of the world in terms of retirement age discrimination eventually, don't worry about RA65.
Don't throw away your BPP, the 55+ year olds signing over to CoS 08 will generate more numbers and earlier BPP, so in fact you will gain more by staying on CoS 99, while these guys sign over.
DO NOT SIGN CoS 08.