I don't see the point of buying a low-end Martin just for the name; I've both heard and played them and wasn't impressed (and definitely wasn't impressed enough to pay the price difference). I can see that it might make a difference in the upper-end guitars, though. Personally, I'd never rule out a guitar based on name prestige/lack of name prestige and I'd never buy a guitar without playing the exact instrument (I'd never mail-order one based on make & model).

I've "met" a few guitars for which I would have given my eye teeth; one was a teeny little 1936 Martin 0-18, one was a friend's big old Fender (the SOB sold it and got a new Taylor that sounded like a fence post; I could have killed him), and the third was a 1960's Guild. They were all great guitars, but then they were all higher-end guitars (at least, much higher end than I could afford/my playing skills would justify).