Personally, I like the I-RACK. I have 2, one black, one OD. Got the OD within 2 weeks of ordering it, which I did about a month ago. You can wear it over soft body armor, but if you want plates, get a carrier.
Hydration - get a camelbak or blackhawk stand alone bladder, and sling it on. No need to modify the I-RACK.
The I-RACK works with my Camelbak BFM as well-
The I-RACK is only $50, but buying the pouches can add up. Note that SDS doesn't have OD pistol pouches. You'll need to get them elsewhere.
ETA: IMHO and YMMV