I actually shot both a Shadow 2 and a Cajunized SP-01 this weekend. I would say both were essentially equal as far as accuracy is concerned. My personal preference is for the SP-01, but I am biased because it is my gun and the Shadow is my buddy's. I will say, the SP-01 was heavily modified (Cajun pro pack, lok grips, TruGlo, TLR1 light), which makes it as expensive as the Shadow 2 in the end. The light actually makes a difference in reducing recoil for me and the Shadow didn't have a light.
I am a hoarder and don't sell my guns, so I do not worry about the resale value. The resale value of the Shadow will clearly be better than a modded SP-01. I've had a blast tinkering with the SP-01 to get it where it is today, so I don't care about resale. I'd say if you love tinkering, go for SP-01. If not, man, Shadow 2 is sweet right out of the box.