Today I was out archeolgizering, when I discovered that there were still some horde left on Ursin. I set upon them immediately.
The only death was an 89 mage. The other rogue and I ended up jousting, but here's where there's the promised ancedote:
I opened on the blood elf rogue and, as cheap was ending, went into spree. Spree can chase a vanished target, kind of, but it doesn't seem to damage them any longer. He did, in fact, vanish, but was well below half even after two spree hits (and my pre-CS-ending attacks). He then CSed me as my spree ended, and went into spree himself. Not three seconds in, I had to trinket-vanish- my health was far too low.
Later we had a similar engagement where I didn't get tricked into tanking any part of a spree.
I'm 488 ilvl, full pvp except mainhand.
He's 483 ilvl, full pvp, one dreadful ring rest mal.
The impression I got from both of these is that spree is potent. Granted, both sprees were against a relatively weak class defensively. The reason I found this interesting is that while I routinely will beat up some horde in a BG or whatever, I don't normally get scared versus a single rogue move in 8700 resil, but I sure did here. Every spree cast by either of us forced a vanish.