I'll try and add something to the discussion but bear in mind that I'm not an expert, and what I'm saying is based on what little knowledge I have and from playing with LTSpice for half an hour.
First read this http://en.wikipedia.org/wiki/Cutoff_frequency especially the bit about the -3dB point. With a standard RC filter with no active parts involved the cutoff frequency, which is the point where the output is 3dB less than the input is set by the equation F = (2*Pi*R*C). Depending on whether it's a high pass or a low pass filter the volume then drops off on a slope above or below these frequencies.
I'm saying this so that hopefully we're on the same page for the next bit, or at least in the same book 
To look at the first stage what I did was remove the diodes and run it at 30volts so there's no clipping messing things up.
With the gain set at minimum so you've just got the 51k resistor and 51p cap in the feedback loop, you get a maximum boost of about 21 dB, if you follow the line down to the point 3dBs lower, ie:18 dB you should see that it's at about 720Hz. Which is where the RC filter equation for the 4k7 resistor and 47n cap says it should be.
If you then make the total resistance in the feedback loop 551k (maximum gain) you get a maximum gain of about 40dB and the -3dB point appears to be at about 550Hz. I think this is because like R.G. says in the TS article the lowpass cutoff frequency of the 51p and the resistance in the feedback loop lowers as the resistance increases. This then starts to interact with everything else so you don't get the answer you were expecting. To verify this if you remove the 51p the maximum gain increases slightly and the -3dB point moves back to 720Hz.
So basically I don't think there's anything incorrect in R.G.s or Jack's articles. The RC filter cutoff for the 4k7 and 47n resistor is 720Hz, it's just that the other things in the circuit change the overall frequency response. They aren't changing what those 2 components do.
They're maybe not giving you the full picture or giving a simplified explanation, but they're not wrong in what they're saying.
I'm guessing its a similar story for the tone control but I haven't had chance to look at it in much detail. I think the portion of the tone control between the 200n and the negative input added to the 220R resistor set the rolloff frequency.
Don't know if any of that helps, it might make someone who knows what they're talking about jump in and tear what I've said to pieces if nothing else 
Once again, that doesn't make any sense. You people are driving me freaking crazy!
If you roll off highs in a negative feedback loop, you BOOST highs in the output, which looks like a bass cut, but what you are actually doing is boosting highs. The point at which the highs are down 3db because of the filter isn't going to be where the bass rolls off 3db at the output, it's going to be where the BOOST STARTS, which is AT THE BOTTOM OF THE CURVE.
I'm trying to help, but I seriously can't put up with this nonsense any longer unless someone is going to back me up. I feel like I'm wasting my time and just going around in circles. The GeoFX article is clearly wrong. We have already seen that with Mohiz's Aplac analysis. I feel like we are moving backwards instead of making progress and it is very frustrating. I am fairly confident that the AMZ article is also wrong. I'm kind of shocked that nobody else can see these clear errors. Everyone just seems intent on kludging the data to fit the GeoFX and AMZ articles rather than stopping for a moment and actually thinking for themselves.
Look, you can't build an RC filter like this:

I'm a newb at this stuff, and even that is very clear to me. I don't see why you people can't understand that. If you still can't see why that can't be an RC filter by itself, then may god help you because you obviously don't understand the very basics of how electrical circuits work.
In order have a filter of any kind, you have to create some sort of voltage divider. Like this:

R1 is not necessary for creating a filter, but R2 is essential! You cannot calculate the rolloff of this filter without taking in account R2, period. You also have to account for R1 in the calculation, but just using R1 and C1 to calculate the filter is ridiculous. It doesn't make one bit of sense. Why is that so hard to understand?
Now look at the tubescreamer circuit. The output of the opamp is the source of the voltage potential. The filter in the gain stage is on the other side of the 51K resistor and the tone pot. The 51K resistor + the tone pot, in combination the .047 cap is what calculates the rolloff. The 4k7 resistor is involved in that calculation too, but I don't understand exactly how it works into the calculation, just that is softens the curve and appears to also effect the rolloff by some small amount. This is, of course, with the diodes TAKEN OUT of the feedback loop. If you JUMPER the diodes, then the negative input of the opamp sees the output without any interference by the filter. The filter is essentially out of the equation. Get it?
Same thing with the filter section. We can disconnect the lug of the pot that goes to the positive input of the opamp, because it doesn't really effect the signal when the tone control wiper is all the way on the negative input side of the pot. That has been established. Okay, now the output of the opamp is the source of the voltage potential that the negaive input "sees". The 1K resistor is your R2 from the graphic above, the .22cap is C1, and the 220 ohm resistor is R1. See how that works? You NEED that 1k resistor for the calculation. It is not something you can ignore out of convenience. It is essential to the calculation of the RC rolloff. To just use the 220 resistor and .22cap in the RC calculation is FLAT OUT WRONG. The actual filter is rolling off nowhere near 3.2Khz, period.
I'm getting really frustrated over this and I'm thinking I'm going to abandon this forum altogether. No offense, but I feel like I'm talking to a bunch of dunces here that don't understand simple concepts. I'm a newb for christ's sake! I know you people are not retards. You all seem very intelligent and educated. If anything I am the dunce in the room, which is why I am so incredibly confused? Am I the butt of some elaborate joke? Hello??!!!!!