I don't think they give enough options for spine/cam combinations. Given that you and Rob most likely shot the same kind of cam I go with his.

That x force like the bowtec is pretty harsh (a speedy speed cam). if you feel uncomfortable with the 3-49 I'd go with the 3-60. I have both and have been shooting both out of a 68# bow. The 3-60 is a touch stiff at 29 1/4" long. Both fly well except the 3-49 tracks a field point better.

Get both shafts, cut one of each and try them out, sell what you don't want.