I am almost positive that the stock mx model will be better than your yfz. It might have a little less power if your yfz is built, but its can hold its own pretty well with the mods stated above me. It will handle better. I have ridden 2 diffrent set ups on yfzs. A stock one, and one with asr and elka. The DS out handles both of them.
the suspension on the mx is amazing i've road various types of aftermarketset ups and for being stock its amazing i race one in pro am it is really an awsome bike for only having a motoworks sr4, and a race ecm, the bike is hard to beat
We have one of each because the YFZ has not sold yet. We had a race this weekend and the clutch went out on the DS so my son had to race the YFZ and he said it did not corner as well as the DS. He loves that DS. Now we play the waiting game on getting it fixed, we have a race this weekend so we will see.
The YFZ is a built bike and he still likes the DS better stock!!