Handlebar risers make is easier to boondock since your "pulling" the sled over at a level that is easier for you. Think of it as trying to tip over say a garbage can, do you tip it over at the very bottom or up as high as you can?...the higher the handlebars "until a certain point" the easier it is to pull the sled over for carving, missing trees when climbing, and boondocking
You don't really notice it when sitting, since your arms are usually just straight out
A boss seat is higher than stock will be, so it essentially makes it easier to transition from sitting to standing. This is helpful more so in a mountain situtation rather than trail riding.