I think the mini-brew is it's own system and they likely engineered this problem out of it from the start.
Cutting that inner step out is crucial. It is just such a pain in the ass to clean around! Sounds like you came up with a similar solution 007. If you private message me I can get you in...
We had been having so many issues with the stock lids on our plastic conical fermenters that we decided it was time to do something about it. This will work for any fermenter with the standard 12" lid. Far better than just buying a gasket!
We started by using a multi-tool to cut out the...