Problem with ph 8 is that it is far far away from Islamabad, I personally know people who shifted there and later regretted as travelling to and from Islamabad is not convenient. Once construction for houses start in Gulberg and Enclave, ph 8 wont be a first choice for many. Ph 8 suits more to those working in pindi.sadar/rawat/, but no doubt PH 8 in itself is very good as far as the living standard and facilities are concerned.
As sayen sb said, times wont remain the same, DHA-2 and Gulberg will become serious contenders to take Bahria's place for high standard living sooner or later.
MR does few good things but yet poops in it, Take example of Bahria phase 1-6, not many people know that Bahria town is dumping all of ph1-6 and Ph7-8 garbage in Soan river on cornice road, resulting in irreversible environmental/natural habitat damage to as far away as Fateh Jhang. Not to mention a foul smell present in bahria town.