1. Should I regem / enchant to more 'EH' style, even at the cost of my expertise (which isn't overly high atm..)?
2. Do you think that I'm wrong in using my current Armory set as my 'progression' set, given my existing options (in my bags atm.)
1. Yeah I think you should. There is no reason to have any gems with DEF on them considering that your DEF is 560 (well over the 540 cap). From your spec you get 6 expertise so lowering it to 20 still keeps you capped.
2. There is a great addon called wardrobe. Get it. Items with Block rating and block value are good for a "trash" set. I keep all of my gear that I get in order to mix and match different sets depending on the situation. When i'm tanking the bosses I use other gear.
I have Outfitter, and use it (have about 8 different sets combining different things...) I'll have to double check that I still need some of that Defense for things like the DPS set, but its a good point, i'll get rid of what i can..