The incision site is no smaller or larger with a laser.....The size of the incision site depends on the dog iteself and not on the procedure that is being done.....
On a male.... the cut has to be large enough to get the testicle through the cut in the skin....this changes depending on the size of the dog and of course the size of the testicles themselves....that is why there are smaller cuts on dogs that are done when they are younger....they have smaller testicles.....However...since they come in all shapes and sizes....the cut has to match what you are dealing with.....
Same with a spay......some females have larger ovaries and uterus.....since they are removed through the incision site.....some have to be made larger....Again depends on how old the female is, if she is coming into or just got out of heat, if she has had puppies and things like that....