The only reason it would change would be because the transfer case is at more of an angle now compared to the drive line. You'd have to have a pretty extreme rake for that to play any role though.
It wont change your rear driveshaft angle. The lift height in the rear is not changing and the drivetrain placement is not changing within the body, so its only the front driveshaft that is changing angle. The weight of the winch and bumper will be placed mainly upon the front axle, very little of the weight will affect the rear.
Thats the point I was trying to make to a buddy of mine the other day when we were puttin down a couple of beers and got on the subject of driveline angles.
He keep saying that my angles were affected by my front end sitting lower compared to the rear....I said "Are you smoking crack?"