Just for grins, here are a couple of scattered thoughts in no apparent order. Hopefully the pictures will make up for the lack of organization.

A number of folks here as well as a number of coin devs are enamored with the Kimoto Gravity Well (KGW). So far, the coins I've found that use this have fairly fast block times. The longest is Anoncoin's 3.42 minutes. Others, from Megacoin through Franco, have block times from 30 seconds through 2.5 minutes. Here's Megacoin with its 2.5 minute block time:
https://coinplorer.com/Charts/Difficulty/MEC
It's pretty clear that this method allows difficulty to track the hash rate fairly well. Let's look at another coin with a 2.5 minute block time - Phoenixcoin:

Let's skip forward in time for Phoenixcoin - here's a look at performance after the Oct, 2013 fork:

This fork is when the team there moved to an average of 100 and 500 block SMA, 10% damper, 20% limit, a 1 block retarget. I don't know if this can be adjusted to work for CAT, but I hope it shows that KGW is not the only way to.
So - all you smart folks in CATlandia - thinking caps people - we need you!
