My Sarah arrived yesterday and I started it right up (still very cold from being delivered).  At first it was very closed in but I let it run for a bit.  This morning when I turned it on it was like it was a completely different amplifier - lots of air, clarity, sparkle, but with the typical palpability in the midrange I would have expected.  As I listened more it started to close up again. Is this the wild ride I'm in for during the break in process?  

FWIW, I'm using a full complement of Cryotone tubes and a pair of well broken in Omega Super Alnico HO XRS with integrated subs.

Yes, break in can be a wild ride. Just buckle up and trust the process, you will be richly rewarded in a hundred hours or so. Maybe longer for the 300Bs.

For break in music I think it is important to play music that covers the entire frequency range and esp. has a lot of transient energy. It is transients that really exercise the capacitors. But JMO/FWIW and all that.