On the PC board thing, that seems to vary not so much by manufacturer but by series. Yam MGs, for example, are most assuredly single-board, or at best a small board-count, design. The GAs are semi-modular, a horizontal board for each panel module = group of 8 or so channels.
But the really good ones (and they're going out of style fast with digital boards) have not only a single vertical board for each
channel strip (like A&H's GL series, for example), but a separate module for each
channel strip. Classic examples of that are any Yam PM series
console and Soundcraft's 800B. Each
element of modularity (vertical board,
channel strip module) of course adds to the cost of the thing, so you're not going to see it at the economy
level consoles.
I think Timmy summed it up pretty well, though: a good engineer can make (almost) anything sound good. The better gear, though, will have better tools to make it easier for you to make it sound good, like two or more swept mids, swept high-pass, metering, inserts,
PFL, true mutes, pre/post switching, more flexible routing options. The first
console I learned on was an old (but then it was new) CR1604. Somehow I made the thing work. Now I mix on a GL2200 with plenty outboard and a good PA every week; I saw an old 1604 in the local Guitar Center a year ago and wondered "How did I ever work on that thing? It doesn't have this and that, and that thing's in the wrong place".
Probably a year and a half ago I drafted up a tech
rider for a band I was working with. A simple thing, really flexible. In that I asked for, console-wise, at worst a
Yamaha MC1204 or MC1604. That seems a fair bottom-of-the-barrel "decent"
console. But good engineers (and I hope I'm a good one; I try) can make almost anything sound okay, and that's the important thing.
), midas, 
