The ramps I had were slightly different to those pictured, they are either newer ones or older ones. They had holes in them, which I guess possible makes them slightly lighter (slightly!), helps dispurse water if your wheels are wet and a possible 3rd benefit might be to increase grip if the rubber on the tyres dips in them (which they will).
Other than that, they're the same. They come in a nice carry bag and stack snugly on top of each other. My only gripe, apart from the high cost, is that they are very heavy - this of course makes them strong, but I'm sure a lighter material could have been used.
Another way to keep them evenly spaced is also to use two pieces of string. That way they're always equal and always right for your seg.
An XT or x2 might not sit in the well equally good as the p133/i2/i167-i180, but would still climb in.
See them in action, on my old i2, in the following video (I used riderless balance mode to effortlessly get the i2 into the boot/trunk of my estate.