I second music's advice on auditioning first before buying. It's not a gamble which you used to have (pardon me for my overgeneralization on your past gambles). PF is really an oddball in head gears, and maybe due to my shallow experience in various gears yet, I haven't come across something which sounds similar to PF series. Well, I plunge into PF 9 after I tried PF 8 and basically have a rough idea how PF series try to convey their musical perspective.
On a side note, heard my friend who just came back from Headphone Mook (talked with FAD's Guru Takei-san) said, the 4 air chambers are the main reason why PF sounds so airy and hall-like. Well, can't wait open the Pandra "Box" and hear the dynamic-BA magic! Rumour was that there wasn't any crossover used. Wonder how true is that.