What suits you?
Have a buddy take a picture from the side of your riding position, its a real easy way to show yourself what's actually happening while riding... if your hunched over, or compensating with your foot positioning to reach the bars, your setup needs work.
I'm riding with a 4" riser together with a 3" drop bar for a total rise of 7" my stock 8" riser wasn't doing it for me, but I prefer to be standing farther fwd on my XP. To each there own of course, think a few guys on here treat it as though it were their junk, Mines Longer than HIS!
If I had to guess, I'd think that a guy 5,11 on an old chassis running a 2" riser is probably hunched over a bit, keep in mind thats what your probably use to but you may find it easier standing up straight. The advantages depends on the what conditions your in. In deep snow boondocking its easier to bring the the machine over with a higher center of gravity or leverage while standing tall. It makes sense to be in a position thats most comfortable to you at rest, generally for most thats standing with your feet hip to shoulder width apart, knees and ankles bent with hands at about hip level. If your backs arched or your shoulders are rolled over or your leaning forward putting a lot of pressure on your bars, these are not good things and I think they might just shorten somebody's day unknowingly.
I think I've gained the ability to deconstruct from a past teaching and coaching sports, but thats my take on the advantages of a taller riser.