To tank in heroic lv80 5-mans, you should have 535 defence, 20k HP and 20k Armor. To be uncrittable -prepared to raid-, the defence should be 540. Only way, gearwise, to reach either is to run as many normal lv80 5-mans that you can get the gear composing these values. Or to spend a fortune in AH to purchase the gear to compose the stats. To which end running normal 5-mans would be ideal, as it would create both wealth and the possibility to get the gear as reward.
The only problem in a top heavy server is the fact, that though there is constant need for tanks and healers to the instances, the requests are always for heroics. Especially when the mode isn't informed in the LFM announcement.
I feel 'gear gimped' as I cannot even participate.