Well, the reason for our three hours of wiping was that I turned on FRAPS ready to record the first kill for posterity. This jinxed the entire raid from the start.
We made P2 I think three times. It took a while for us to work out who should stand where, where we needed to run and how the tanks should ferry the mobs to the boss to be killed.
It is such an unforgiving fight - any mistake is immediately pounced on and causes a wipe. The guardians seem to spawn faster and faster throughout the phase and you will eventually be overwhelmed even if you execute the strategy reasonably well. It is a tightrope walk between trying to be fast and kill the adds quickly, and killing them too fast so Sara is unaffected, while all the time you have things that can go wrong - missed interrupts, standing in the clouds, range issues for the healers, etc.
I need to change my UI round so my interrupt key (which is bound to the same button on all my characters and alts) is nearer the keys I use to dps. That is going to be annoying to relearn. Sigh.
Positives - we definitely got better over the course of the night, to the extent that errors are now met by me swearing loudly over vent at the offender, rather than giving a rueful chuckle. Achieving P2 regularly is not too far away. We certainly had the tanking down by the end.
I made sure I locked my healadin alt to the raid at the end of the night, since I will raid a new raid on Friday to do hard modes. I can keep the old raid ID on my alt to ensure that I can have more tries on Yogg in a week or two...