You assume that you will be flying the MAP with one engine and therefore you need to know your OEI climb gradient to be able to choose which minima to use. If you have an escaperoute for departure from the same runway, perhaps once in a while it could be accepted to use that procedure and then use a lower minima, but remember that the GA performance calculations and TO performance calculations differ in their requirements and that it is not (in a strict world) possible to just decide to use normal departure procedures for GA.
We had this problem in Sarajevo when I flew there. In bad weather it was more advantageous to be as light as possible to get a better climb gradient to be able to choose a lower minima. One good way to keep track is to ask the performance calculating company to produce a speedbook with the gradients stated for each weight.
Edit: I see the two previous posters say that the performance is based on all engines operating. Perhaps it is so for Perf Class B, so be it, I'm only familiar with performance class A. In any case, I for one would not want to be below minima if I didn't have single engine performance to get me out... All takeoffs are based on it so why not have the same reasoning for go arounds?