Definitely go with JC/BS IMO.

You already have mining covered on another toon, and BS will net you the same benefit with the two sockets it offers if you put +stam gems in them. But it also offers the flexibility to configure differently if you want. While it's true that the BS epics are BoE - its very convenient to be able to craft your own items, without having to wait for guildies or be gouged on pricing from buying on the AH. And if you're already making titansteel, you should have the mats covered as well.

Having a 2nd JC will allow you to cover off different patterns that might take your 1st JC months to acquire...besides the obvious benefit of the prismatic jewels and the figurine trinkets for your tank.

Although both professions are expensive to level, money shouldn't be a problem if you already have a team of 80's. Just grind out dailies - this gave me enough money to furnish 2 teams of 5 with epic flyers each and have both of them at grand master engy on each toon.

Cheers,
S.