Sherpa's is the king of the food delivery services here, but have you tried any of the others?
I was chatting with people at B Real restaurant on Fumin Lu -- the new Bánh mì restaurant -- and I asked when I would be able to order delivery from them. I live near Laoximen, so a one-way taxi ride to B Real would be about the same as Sherpa's delivery fee. I learned that in addition to Sherpa charging the diner rmb15/30/45 bucks, they also take 30% of the bill from the restaurant! So B Real isn't going for that kind of racket.
Based on Sherpa's success these past 10? years, there have been a whole bunch that have started up: I think NYC Deli and Munchies both prefer Mealbay, and B Real was talking to a Chinese owned deliver service.
I have been using Sherpa's because their web ordering makes things very easy. Do you use any others for food delivery in Shanghai?