I also have a Spacehorse. I don't use it for grocery runs, but have used it for credit card touring. I've been using a velo orange porteur rack for the past couple of seasons. Depending on the quantity you want to haul, it works fine. I used a couple of rolltop panniers and a rack top bag, plus the occasional cargo net to lash more loose stuff down. Total weight carried generally in the 15 pound range. The steering gets a little slow, but doable. I think if I were doing grocery panniers like Banjo Brothers, and the like, and I wanted a front load, I'd probably go with the pass and stow rack, as it offers a little lower mounting point for panniers, which keeps the load lower, and frees up all of the rack on top for odds and ends or larger sized items.