A picture is worth 1000 words ...

Very cool!

I have been experimenting with this recently and I have found that the different patterns give diff EQ characteristics (ie one is brighter than the other etc)

However it strikes this must be because of the different reverberations/EQ happenings in different places in my recording room - which the different polar patterns will catch to a varying degree.

Absolutely!
In Fig 8 and Omni you'll get the early reflection off the back and side walls and those reflections are usually brighter and since they are a 'reflection', you hear them a millisecond or two later - separated from your initial transient and making them more apparent.

If you have a shitty room, as long as you use a cardioid mic (sm57) close to the cab, it won't matter. Hell, you can record outside if you close mic with the right polar pattern.

Cool thread The polar pattern can make a very big diff in terms of the sonic content of a given recording. Blending various polar patterns and different mics can offer a huge variety of tonal options. It's why I use more than one cabinet sim and two mics on each one when building patches in THU. Blending all off these together makes a huge impact on the quality of the guitar tone. Using just a single 57 is a traditional approach, but I've found it to sound too boxy and spikey compared to using several.

Here is an audio demo of various polar patterns.

That's a great video,