Here's more detail explaining the specifics of what the others are talking about.
In general (some background)-
There are a couple of different yet interrelated things going on which affect the differences you'll hear between those two microphone configurations. One aspect is the effect on playback imaging, another is the effect on the amount of direct sound verses reverberant sound you’ll hear on playback. Of those two basic aspects, most listeners will prioritize a good direct/reverberant relationship over good imaging aspects, but both are important to a good recording.
The direct/reverberant aspect affects how much room and audience sound is heard, blended in with the main sound arriving directly from the stage and PA. It affects clarity and how reverberant the recording sounds. The imaging aspects affect how wide the playback image sounds and the distribution of the sound sources within that playback width.
There is overlap between these things, some imaging aspects have to do with how evenly the direct sound is distributed across the apparent playback width and how reverberant the stuff in the middle sounds compared to the sides.
Here’s the clincher-
It is possible to adjust the microphone-spacing/angle relationship so that you have various setups which produce similar imaging but with different direct/reverberant aspects. You can also work it the other way around.*
Specifically-
ORTF has an SRA window of about +/-48° or 96° total
DIN has an SRA window of about +/-50° or 101° total
The SRA of both is similar, being only about 5° different.
The SRA window of DIN being slightly wider than that of ORTF means that the resulting playback image will sound slightly more packed together into the middle of the playback image. The sounds arriving through that wider SRA widow will essentially be squashed together more to fit the same available playback space between the speakers. That’s the imaging part and hints at why the description of the relationship is called the Stereo Zoom.
Now, if spacing between microphones changes, but the SRA is to remain similar, the angle between microphones needs to change to compensate for the spacing difference.
ORTF has a spacing of 17cm and an angle between microphones of 110°
DIN has a spacing of 20cm and an angle between microphones of 90°
That’s a difference in angle between microphones of 20° which is likely to be more significant in its effect on the direct/reverberant aspect of the recording than the 5° difference in SRA has on imaging. That part of this is what page is talking about.
[edit- one overly simple way of saying this is: the reason tapers often use DIN instead of ORTF is because it points the microphones more towards the source, which can be helpful in a less great sounding room, even though ORTF might sound better in a good room. That's a gross simplification, but a way it's commonly thought about. All this other stuff is an attempt to explain some of what's really going on and the deeper implications]*Quick aside- That’s more or less what’s going on with the
improved PAS method I posted about recently. In that case the primary goal beyond simple setup simplicity is achieving the highest possible amount of direct sound compared to reverberant sound from any given recording position. With PAS, that’s accomplished by pointing directional microphones directly at the PA speakers. What’s going on behind the scene to determine the most appropriate microphone spacing values shown on the PAS table is figuring out what spacing will produce the most appropriate imaging based on the angle between microphones and the width of the stage as seen from the recording position.
I’ll try an post more on ways to best use the Sengpielaudio visualization applet which aaronji posted a link to later to help understand all this..