Great thread SR.
My own experience of base training has been very positive, even though I have never raced further than 1/2 marathon. I have built up a base over three months for each of the last two winters, and really improved my times the next season as a result.
BR, I think the point is not how far John Mayock races, but how many miles a week he's doing in his quality phase when he's peaking for races - more than most club runners when they're training for 10k I'd guess. IMHO, the important thing is to do a greatly, but gradually, increased number of miles than you yourself would do in your racing season, and to run the vast majority of them aerobically. Therefore, what is mileage in a base phase for you is relative to what you do in the rest of the year.