I currently have blacksmithing and mining but I am in the process of getting rid of mining for jewelcrafting. This would really help on min-maxing my stats. I know a good amount of players in my guild has 2 crafting proffesions and gathering proffesions on their alt so I figured I'd joined the club.
Making all raiding members min-max their proffesions will not work in my guild. The only time it worked really well and everybody in the guild was up for it was waaaay back in the 40man raids where we ended up getting in the top 5 U.S Horde guild when Naxx just came out. Those days ... are over. Even with Ulduar coming out gear check won't require everybody to be 100% min-max to clear it.
Right now I am leveling up mining on my lvl 62 DK. All I can say is ... finding Tine ore is a B!tch! I'm stocking up materials on the way so the minute I drop mining I can immediately proceed to leveling JC.
I figured getting extra sockets from blacksmithing and extra stats gems from JC is a really good combo be it tanking or DPS.
I must admit that this decision has got to do with my friend, who is a fellow TG warrior, is beating my Bloodthirst by a good margin. Granted there are small(and I mean small) differences in gear but I can't let the gap widen or else I'll find myself on the bench come Ulduar. That would really make me a sad panda, I live for the first boss kills after a dozen or so wipes =). There's something about learning an encounter, adapting and beating it.
The drawback of course is losing my gathering proffesion AND having to level up my alts in order to max them. My druid who is almost lvl 71(enchanting and skinning) and my dk lvl 62(mining). I have invested about 2 hours into this endeavor and it looks like I need around 6 hours more!
Hopefully I can finish this project of mine by the end of the week.