I don't know about comparisons, but I have one of these and it's pretty awesome in it's appointments, playability and sound for an all mahogany parlor, especially at what I got it for used. I'd like to compare it side by side with the Martin O-28VS I liked so much in the store when I played it, but which was rather quiet, even with a nice spruce top, and was priced at $3K more.
http://alvarezguitars.com/guitar/mpa66shb/