Rim experts: Diff. in Davins/Spreewells & spinners

Ok, I'm trying to decide on whether to upgrade my current chrome 20s to chrome 22s or chrome 20s with bolt-on spinners rims. Right now I'm leaning towards the 20s with spinners because I don't feel like paying for a set of 22" tires when I have a set of 20" tires with less than 5k miles on them. Also, I would like to spend as close to $2000 as I can because I already pair $1500 with tires for my current 20s. Before I buy these spinners, I wanted to know some facts and opinions about them. I have heard from some people they are just as good as the real Davins and I have heard from others they barely spin at all after the car stops. My friend just got chrome 22s with spinners put on his F-150 last Tuesday, and they kept spinning for over a minute after he stopped. How long do the real ones spin for? Do the bolt-on spinners spin fast? Thanks.