Grats on your drake, that one took me the longest to get for pre-cata dungeon mounts.
As for Sarth, yeah, it all comes down to how many defensive cooldowns you can stack. As a rogue I am pretty well off, evasion, ~25 second 50% damage reduction ability, smoke bomb reduces damage by 20%, cheat death, and a glyphed cloak of shadows reduces melee damage by 40%. It's all enough for me to survive the drake enrage, almost, just need to push out a little bit more dps which hopefully my recent upgrades will allow.