Before I give my answer, I should point out that Suyi at Auber Instruments is super helpful. He has suggested to me that for a large cooker with a lot of latency (like the tabletop roasters) setting I to 0 (thus turning the controller into a PD rather than PID) is the best way to go. I haven't done that because I have been happy with the settings I found. But I will try it when I have a little spare time.
I saw back a while your PID settings with a roaster. are they still 250-900-100 or did you find better settings. I used auto tune and I hang below temp a degree or 2 longer than I like while it stabilizes
Since my original post, I have also purchased the 3rd generation PID with auto-tune. For the roaster full of water, auto-tune came up with P32 I 998 D 499
Note that a couple of those settings are outside of what you can manually set. So, when setting manually I use the closest settings to that that the PID will allow.
Those settings are rock solid once it come up to temp. I start with hot water in the roaster since my hot water heater is a more efficient water heater than the table top roaster. I let the water in the roaster get up to temp before I add the food. It stabilizes quite quickly -- but I do wait until it has stabilized to add the food. These table-top roasters have a LOT of latency due to the double-walled design.
Also, make sure to use Fahrenheit settings as that give you better granularity (since 1 degree fahrnenheit is about 1/2 degree C).