Charle,
I made a similar lift to the one pictured back in High School as my class project for machine shop class. I used a copy of the picture you posted from some magazine as my guide for building it. I scrounged steel material from our scrap metal pile at our IH dealership. It works pretty good but my ramps are straight so it takes a little work to get the back end started up when you are raising a Cub Cadet up from floor level. (I call the winch end of the lift the front.) I see the ramps in the picture are bent down at an angle at the back end which would definitely ease getting the back arm to rotate up since it doesn't go clear over to horizontal.
As for its usefulness, I found it most useful for loading and unloading Cubbies into and out of the back of pickups. It does comes in handy if you need to get underneath to work on something, like removing the steering box, but you are crawling around underneath in a squat position which isn't the most comfortable position to be in for extended time periods.
In reality I never found that I could really do much actual service work on a Cub Cadet while on the stand because I was usually needing to get at something from on the top and if the Cub Cadet is already at waist height or above, then you are having to crawl upon the lift to get at what ever it is you are needing to work on and I would just as well have it on the ground in that instance rather than risk falling off the stand.
Using it for removing blades from the mower deck for sharpening works great for the center blade but access to the outer two spindles is usually limited by the wheel ramps. I always found it easier to just pull the deck, flip it over, grab a wood block, hammer and wrench and I could have the blades off in a few minutes and ready to sharpen versus putting it on the lift, crawling underneath the stand, trying to hold the blades stationary while loosening the nut, all while getting a mouth full of grass crud and dirt in your face and eyes to boot. My $0.02.
