Epic Flying Mount Opportunity CostFollow

So, I'm a protection warrior at 70, in the process of gearing up for heroics/kara. I had enough gold for my regular flyer as soon as I hit the cap and now am considering saving up for the epic, currently sitting on around 1500g. The question I found myself asking is: Do I really want to spend that 5000 gold?

I hesitate because I've been thinking about dropping my mining skill to power-level engineering (I have blacksmithing capped as a swordsmith, will probabaly switch to armorsmithing if/when I grab a sun eater or king's defender.) The engineering goggles are amazing, and I could use the stamina trinket and epic gun as well.

My other reservation is that I understand, at least initially, flying mounts will not be usable in the new zones that the next expansion will bring.

I know everyone says how much easier it is to make money with the epic flyer, but do you think its worth delaying the major gear upgrades I could accomplish with engineering?

you can't use the flying mounts for bg pvp. you unlock a few quests with epic flying skill. you can farm so utterly faster than you can image, it's hard to explain. if you have mining or herbalism, the uber mount pays for itself, if you actually go out and farm.