On my tank, i've had Alchemy as long as I can remember purely for the buffs. But recently i've started to dislike it. After seeing the items through JC i've been thinking about dropping Alchemy for Jewelcrafting. As a tank would this give me the best options. I see myself getting more out of the gems and Monarch Crab trinket then having pots.
Bear in mind the costs of powerlevelling another profession to at least 350. (LK recipies start at 350.)
I was lucky enough to pre-farm most of the mats for my DK to powerlevel both BS and JC to 300. I wound up changing my mind and smelting up to 290 and powerlevelling my JC to 240 the first night. I then ran into an annoying bottleneck. You need Flask of Mojo to get out of that range. I wound up farming 60 flasks by running lowbies through ZF in exchange for all the flasks. (None on the AH, or up at 9g each.) Only wound up needing 40 flasks. I then ran into a snag at the 280 range because I didn't have enough of the final gems to get out of that range. I wound up spending another 700g for those last 20pts. Outlands went fine because I got lucky and bought a bunch of green gems well below market rates. Most green gems are at least 2-3g each on my server. The next snag was at 340 since I didn't have enough mercurial adamantite for those final 10pts, so I wound up just buying ore to prospect. Mercurial Adamantite was up for 25g each on the AH, so it was just cheaper to make my own. Cost me another 200g to get to those final 10pts.
I'm currently farming my own LK mats to move on. Might just cave in and power it up a bit more.
It'll balance out in the end, but right now it just seems like the JC trinkets are better just because of the slots.