Once I get a new job, I'll reward myself by upgrading my Extreme to have an outboard PS too. I talked to Mikhail about it at CanJam. He suggested leaving the IEC on the Extreme. This means two power cords are needed, but has the advantage of not sending any AC from the outboard PS to the Extreme. Are you doing this too? I forgot to ask what is then powered by the Extreme PS and what is powered by the outboard PS.
On an interest side note, Galina (Mikhail's wife) is now the business manager at SP. One now gets schedules, etc. from her. Mikhail said he was relieved to no longer have that responsibility. So when asking how long something will take, you have to ask Galina. Hopefully this will greatly improve SP's biggest problem. On the plus side, it can hardly make it worse.