There is no complication with the actual fore-aft setting or its effect on saddle height, but usually when you move the saddle fore-aft it changes your leg reach to the pedals. So you generally do need to adjust saddle height. If I remember correctly, the quick and dirty is this: for every 10 mm you go forward (backward) add 1 mm extra and raise (lower) the saddle 3 mm. The extra horizontal movement accounts for the backward slant of the seat tube. Sounds crazy but it works.