These days I find myself wearing a lot of DPS gear not just for leveling, but for tanking instances. For a particular slot I'm either using tank gear with block value on it, or straight DPS gear, for the most part. So far, I have not run an instance where I've needed to swap gear out for more health/avoidance/mitigation.
For soloing, I wear my old DW dps set with a shield. I still solo in def stance for the revenge/dev-->S&B train, but with about 900 more AP, 10% more crit, and about the same block value as I had in prot gear. (more str, more BV).
I do *more* dps in def stance vs battle/zerker in every situation where I'm getting hit. When I'm getting hit, revenge+dev feeding the free Shield Slams pretty much keep me in rage, not to mention the free HS's from the Revenge glyph. The only time I need an offhand is DPSing as prot where I'm not taking damage. Soloing in def stance also lowers my downtime considerably.
I'm currently lvl78.
For soloing single targets, I'm currently wearing the full savage saronite set and for the neck, ring and trinket slots I'm using +AP +crit trinkets.
Pretty much it works VERY well, barely take any damage and kill mobs in 3 crits.
For aoeing, I simply swap out and put on a couple of def/block pieces and block trinkets then do the ol' thunderclap/cleave/shockwave spam.
My intentions (and this may change) is to run an OT spec. Take improved intercept, get the glyph, and improved spell reflect.
So, I guess I'll need the shield and just have to eat the DPS loss when OT'ing single bosses.