Peace, I owned a Gurian S3M(Size 3 mahogany) and and S2M (size 2 mahogany). They 'didn't give it up' easily, but once one's hands adjusted they were magnificent sounding guitars and a 'soundman's dream' as one VERY particular, opinionated and experienced guy once told me at a gig. The size 3 was similar in size to a Guild F-30 but had a much more 'punchy and defined' bass response very similar to an Olsen. See Jonatha Brooke's video 'Lullaby' on youtube to get an idea of what a Gurian sounded like. She uses an Olsen, but it sounds just like my old Gurian.

The S2M didn't have the body capacity to be used as a vocal accompaniment guitar, but was an excellent 'lead' guitar and could be soft and mellow or bold and brassy as the song needed. They both miked incredibly well w/an AKG C1000 in combo w/an SM57.

Had a friend who had a Rosewood Jumbo can only say it was the LOUDEST guitar I've ever heard next to a Rainsong jumbo. The secret, I believe to the sound was that Michael Gurian used 'fan' bracing ala a classical guitar rather than the X or 'double X' bracing used on most steel string acoustics.

I COULD go on, but this IS a Martin thread, after all. Sorry about the hijack, Seamus.