Gary it really is a matter of preference. It does for some folks make it easier to see the item you are cutting, especially when sitting. if you cut standing up it does not do much for you. Personally I have my raised in the back so that it tilts a bit toward me, it helps me see where I am cutting better. With the table sloped there is one issue... the work will tend to slide toward you, on a table that has no slope on it the work remains in position and you do not have to hold it while cutting.
DW