Good question.
I think I only have one XRCD a Hall & Oates? So I can't comment on those.
First, the naysayers will always pipe in and say it's just 16bit/44.1Khz a waste of money, let them be.
I have a few opinions having purchased many SHM CD's. Sometimes by luck, by there in a Japanese packing, box sets, mini LP's, etc.
They are a little thicker plastic, if you have a CD slot in a car, many times the SHM CD will get stuck coming out just for that tiny bit of thickness.
When a person buys anything Japanese produced the quality, packaging, etc. is better. The big box sets come with an outer plastic fitting sleeve protector that you get no where else.
But what about the sound?
My personal opinion is that they have a better midrange and the low end plays a little softer, more analog, I guess you would say.
The Dynamic Range is equal mostly to it's RBCD brother, generally, never worse, occasionally a little better.
I have had some Blu Spec CD's over the years and I think they are good to.
All and all in is just one big crap shoot and to each his own.
Then there is the question of CD players, of course there are better rated then others.
Being we are on the big The Who box set coming, my logic is I want to get the best version of what is available, only on these big iconic releases, like The Beatles, etc.