DH and I decided he would have a vas, after we found out we were pregnant with our 5th child (our only 1 together). He had no major problems. One thing I did tell him, and still do, that IF I got the desire for more children later on, that we would look into adoption or foster care. And IF God wants us to have more children "naturally" then He is a BIG God and can make it happen (we know of at least 1 couple who has had a child post vas. and all checks up to that point were "clear"!)
But over all, definitely pray about it, and really consider what you are doing, more and more urologists are doing them where they are near impossible to ever reverse (they cut, snip, tie, burn whatever they can do)