I play the 901 *R* w/NS950S straight out from the box! No changes except the make the grip larger with 3 wraps. It's one of the best sets I have ever used. It's cast isn't it? If it is, it sure feels softer than some forged irons! The set is fade biased, and in the beginning you'll find your balls going right but it's quite workable and not too difficult to hit it "straight(er)" or right.
Aesthetically, the finish is beautiful. You really have to see a real set to appreciate the finish. Unlike the traditional Honmas, it doesn't dink that easily either, so I don't think iron covers are necessary if one is not too rough with them. I carry my own bag sometimes, and use caddies & buggies occasionally, and despite the knocking around, the finish is holding up really well.
The sad news is that....I don't think I'll be buying another set of irons anything soon
Cheers
-Keng