And does anyone know if bfgminer supports the variable difficulty being talked about here?
Yes, for the past several versions. Your worker hashrate needs to be high enough, though. Roughly 20 shares/minute is the threshold I believe. I have a 1.6Ghps worker (~22 shares/minute) which never sees a difficulty higher than 1. A 12Ghps worker would see a difficulty of 8.
We have one bfgminer setup with 24Ghps total, so I'm assuming we should see the difficulty rising. What this quickest way for me to check on that, and is the difficulty level something I can set myself?
Thanks for your feedback...
To check, just connect your miner to the pool (-o
http://mint.bitminter.com:8332 -u -p ) and wait; whether you use stratum or not doesn't matter. It will start at difficulty 1 but in a short while (a minute or two) you will see the difficulty increase as the pool gets a better idea of your miner's speed. BFGMiner displays the target difficulty in real time as shares are submitted, so once you see that number change from '1', you know vardiff is working for you.
Something like this (the 'Diff 32/8' means that the target difficulty is 8 and the submitted share had a difficulty of 32):
[2013-02-24 21:19:11] Accepted 08e39d0a BFL69 pool 0 Diff 32/8
In your case with a speed of 24Ghps you may see a difficulty of 16. As for setting this yourself, no, currently that is not possible at BitMinter. It is automatically adjusted by the pool based on your hashrate.