First of all, there's a revelant section for everyone to read in Gwern's well-written FAQ. It mentions the opinions of lots of people within the DNB community.
http://www.gwern.net/DNB%20FAQ#are-strategies-good-or-bad
I recognised that subvocalisation or repeating the position and letters in my head was really something that was inevitable. My personal opinion is that 'intuition' is far too unreliable. When I began DNB in Sept 2011, I tried the intuition method and it simply just prevented progress. Some days I would get to D4B and other days I would struggle on D3B or lower and the pattern did not change for a while. I recognised that subvocalisation or repeating the position and letters in my head was really something that was inevitable if I wanted to progress.
Over the course of my still ongoing DNB training ( now D8B peaking at D9B), I've found that although strategies provide a large infrastructure to help you complete the task, perhaps 40-45% of my correct answers were due to "intuition". I just simply had a "feeling" that something was right without really seeming to actively recall it. I realise this is subjective and hence I am going to test the two theories ( see below)
My theory therefore is this: For those who simply do subvocalisation and chunking (NOT speaking/following cues with eyes), your "intuition" level or the level is perhaps a few DNB levels lower than your current DNB level. I feel this accounts for the effect of the strategy. For example, if I am currently at D8B or so, then my brain probably intuitively remembers 4 or 5 items back - hence intuition level of D4B/D5B. Therefore, as your DNB level rises due to the strategy, you are also simultaneously changing neural pathways so that your "intuition" level or true WM also rises.
Nevertheless, I am open to trying the intuitive method again despite my previous failures because the ultimate purpose of improving WM transcends my belief about the strategies. I shall be separately trying to begin a new DNB training regime using only intuition like the user DarkAlrx mentioned in Gwern's FAQ. I shall report back results ( hopefully positive) soon!