Not too much more to add. I coveted the stainless on my wish list when looking for a Prevost. The H3's are quite beautiful and striking as well. The floor plans on the H3 are different because of the drivers seat being low in front. I believe the H3s have a more defined living rm and galley.
My XLII is 12' 7" with the satelite dome so not much difference in height.
I would say storage down below is the advantage on the H3 .
When looking back, I did not know much about Prevost nor the difference between H3 and XL Coaches. But I had owned several Plastic Custom Paint Coaches and really fell hard for the look of the XLII. Still feel that way although Liberty has some beautiful H3-45's on their Web site.
At Prevost in Mira Loma, I spoke with a Bus driver of entertainment buses. I asked him what he prefered to drive. He said the XL was preferable to drive but the H3 was better when Parked. So there you go.