The 1080i issue may be not quite so important as I thought. At least not for the BBC. Having just re-read their guide for HD production whilst they may require a specific format such as 1080i for a show commission they will in most circumstances accept 1080 25p. Which will be broadcast 1080 25 psf (interlaced signal, progressive frames) However you may not be this lucky with other broadcasters.
At the Broadcast Video Expo in London the other week there were a huge number of seminars on RED and RED in post, plus RED Ones on many stands. It seems they are taking off in broadcast but mostly for Drama and TVC spots, not more mobile applications. I think the Scarlets will be the game changer for all this due to the form factor and hopefully the more approachable 1080 RGB recording format, which I hope will be well supported on common affordable edit systems like FCP and be able to playback on a standard system in realtime at full res without a RedRocket. Hopefully this format will also mean smaller file-sizes since it will be lower resolution than the full 3k R3Ds, making buying a suitable sized portable hard drive to hand over deliverables a cheap give away media option.
Having said previously that I saw myself going in a Documentary route, I realise from working on a recent shoot that I love working on Dramas. So I may well go high end and get a RED Rocket™ to DIT on red shoots, then eventually get a s35 or F35 Scarlet (for nice filmic shallow DoF control) + 2/3" fixed (for high frame rates + bundled modules) as I work my way up the camera dept and once the RR has paid for itself so I'm getting less and less worried about these ENG/EFP specifics. I don't envisage doing any news, and EFP can usually afford to spend some time in post and with a RR and hopefully soon direct support for the RR in FCP and Color I'll be able to offer a nice efficient workflow to clients.