Umm, I have a sled deck. And, this year, I upgraded to a D8. One of the reasons I chose to change sleds rather than add 'go-fasters' to my M7 (loved that sled) was to get a reverse feature.
My wife's sled still does not have reverse. I want to get her one with it, but right now, she says 'no', so we have both.
I align the ramp with her sled, take off the brake, and then pick up the front end of the sled with the front bumper. Then I just take small steps toward the rear of the truck, and after a couple feet, the sled is balancing on the edge of the flat portion of the deck (I have an 8' long deck, plus a beavertail). The hardest part, is the skis want to **** sideways and catch on the railing, but I've sorta learned how to mostly prevent that.
Mine, I fire it up, let it idle for a bit, hit reverse, and gently bump the throttle, and ride it down. I still have the OE softer springs, so my snowflap currently wants to get caught under the track when the back of the track finally reaches the ground, but the box that arrived today should help cure that issue.
(I went to the 375/47* Polaris springs)
All in all, if you're big & strong, you can get them off w/o too much trouble, but reverse is waaaaay nicer.
Given the choice, I'd rather use a deck than a trailer, even if my sleds don't have reverse.
Tip: I have found (others' experience may differ) that when the sleds DON'T have reverse, it's better to unload them onto the flat ground, rather than back into a snowbank. Gravity does help get them down the ramp easier. Now, with reverse, the snowbank option is kinda nice.
PE