Ive got both, in both regular and short lengths.
My opinion is the xlite is more comfortable lying still, especially on back in regular length, but a bit more fiddly.
Nothing against it, but there is something to be said for a more stable pad if you move around. I slept 40 nights on my xlites this year and am quite happy with both of them.
The xlite short, is really too narrow at bottom,makes it too fiddly. The prolite plus short is better. But I will still take the xlite because it weighs 8oz less in short.