I think I know the guy...
@HardyFool!! There is a video of his system somewhere in this thread.
I feel like 2.5 gallons is about a sweet spot. What did you not like about that size? For that size I could see the Anvil Foundry 6.5 gallon system for brew day, the SS Brewtech 3.5 gal Brew Bucket Mini for fermentation (maybe with a small fridge for temp control) and some of the Torpedo 2.5 gallon kegs.
That said, I just brewed my second all-grain 1-gallon batch using my setup up a few posts (the 2 gallon insulated jug, a 3 gallon kettle, and the Little Big Mouth Bubbler fermenter). I brewed a few other 1-gallon all-grain batches in the past, but the insulated jug helps and I really like having a fermenter with a spigot for 1-person bottling.
I tend to brew investigative batches in the one gallon size. They have mostly been to try out different hops or base grains, but I hope to use that size for recipe trials in the future. I like a larger fermenter so I can get about 9 bottles out of a batch. That gives me enough to sample myself and to bring them along to a homebrew club meeting.