Originally Posted by
Sidira
You'll be able to dual spec, spec one arcane the other TtW and swap see how each feels to you. TtW scales better with haste over crit, so having a lot of haste isn't a bad thing. There are still some RNG factors related to crit, but the reason that FFB was so crit dependent is that its normal hits were puny compared to its crits so the object was to make FFB crit as much as possible. With TtW fireball hits decently hard so it's not as mandatory that it crit. Obviously critting is a good thing cause it's more damage and more chances at HS procs, but not nearly as detrimental to the build on a whole as having low crit with FFB.
Personally, I try my best to stay above 500 haste with FB, though that's becoming exceptionally difficult with the shoddy itemization of Ulduar gear. I'd say anywhere in the 450+ range is adequate, possibly as low as 425.
As for the VH trinket, take what you can get I guess. Some people swear by arcane even now, but in comparison to the other mage in my guild who dual specs arcane, it doesn't reliably beat out fireball.