I agree with Perry. My basic thought is that the server has a
fairly considerable advantage in singles, and in doubles I look
at the serve the way Bear Bryant used to talk about the passing
game in football "Only 3 things can happen, and 2 of them
are bad." I do think the server advantage in singles is notably
more important to the way a singles game goes than the reciever
advantage in doubles.
As far as how much I consider it in handicapping. I put a good
bit of thought into it in singles, particularly a strong server
in the 1 post or the 7 or 8 post (thinking runouts, to go with
a previous question of the week.) In doubles, I put very little
consideration into it, other than possibly looking at a 2 or 3
team that features a strong serve stealer in the frontcourt.