I own a mid-90s dr28-h copy. think it was a special edition, with the herringbone inlay. absolutely terrific guitar, virtually indistinguishable from martin equivalent in sound and feel.

whenever i mention it to knowledgeable dealers they stress that it will hold its value and try to convince me to part exchange it for whichever of their guitars i'm interested in. i paid about £500 for it in (i think) '96, though i think the guitar was a couple of years old at the time. it plays much better than a lot of more expensive models (including newer martins).

of course quality will vary from model to model, year to year, but personally i wouldn't part with my sigma. seriously worth trying out at least if you are looking at martins- if the brand isn't important to you, you can get an older, played in guitar for much less than a brand new martin and still with that martin feel.