I've merged both threads since answers were posted in both.
IMO, after spending years pondering this, I've decided to stick with the HD-800s and orthos. Why? Because I could go with SR-009s and a BHSE, but that's a $10k investment in an amp that can ONLY be used with 'stats and a pair of headphones that can ONLY be used with a 'stat amp. If there is anything I don't like about the 009s, such as them being unsuited to some kind of music I want to listen to, I'm stuck with the result. It is a shame, because in many ways they are outstanding, beyond anything else, but I also only have a handful of recordings that are really capable of showing that. I've also found a HD-800 set-up that suits me perfectly and the difference I intend to spend on suitably excellent near-field speakers, since I don't have to use headphones all the time now.