I've got a 7 bike VelociRax and am saving up for a 4 bike rack too. I absolutely love this bike rack. I will always use a vertical rack from now on.
For loading and unloading, I just grab it by the lower bar with my chest against the center bar. I will slide it out and lift it like a giant cross. I also picked up a cheap furniture moving dolly from harbor freight. I took some 2x4's and built arms that come up and hold the lower bar with the hitch tube resting on the bottom of the cart. Then you can just slide the rack out of the hitch, set it on the cart and roll it into the garage.