My buddy has a Surly Disc Trucker, has had it for years. He doesn't have a car, so it's his primary form of transportation around town/school/work/etc., so definitely a grocery hauler as well. The bike came with the Surly racks, all of which have been bombproof (though heavy). He changed the handlebars long ago, and recently switched to Tektro hydraulic brakes and finds them excellent (he used to work as a mechanic at a bike shop, so they helped him out with the switch). He's done some touring, and now we're both getting into 1-3 day bike packing/camping on gravel and forest dirt roads. He's not heavy himself, around 200lbs, but that bike seems to be built tough. He mounted Schwalbe Marathon Mondial 26 x 2" tires earlier this year. and loves them. The whole tubeless tire thing is something he hasn't delved into yet, though I run tubeless on my hardtail and gravel bike. How wide are your 700c tires?
I wouldn't skimp on racks. Buy good quality racks, Surly, or Tubus Logo Evo. I don't have them myself, but the Tubus get great reviews. He's been using Thule panniers for years, but wants to upgrade to Ortleibs. Mainly because it's time, they've been well-used.
Good luck on the dieting!!!Here's his Surly DT in Wawona/Yosemite on our ride yesterday. Plenty of Surly Trucker fans around here who should have more info for you.
eric/fresno, ca.