There she is again =)
The Hi-Rider eliminates the need for a riser in large objective scope use. In my opinion, the fewer links in the chain, the stronger the chain as a whole. By eliminating a riser, it's one less variable that needs to be concerned with.
For what it's worth, I sell about half as many hi-riders than A3's, which doesn't sound impressive until you realize that we sell around 500+ A3's a week sometimes.