1) He doesn't have an ax to grind / an LLM to pimp out, so he's relatively even-handed
2) He uses the same (secret) test data for each model, so his testing is resistant to cherry-picking/finetuning on tests
3) He likes weirdo role-play prompting, so he has a very good sense of the edges of refusal and alignment tuning
4) He picks up stuff well before it hits the only other fair testing I know of, the chat arena
5) I think asking stuff in German is at worst neutral, and at best useful for testing capacity in edge cases.
Practically speaking, his 'preferred' non-giant models, Nous-Capybara-34B and Mixtral both are excellent in comparison with some of the others he looks at, and good recommendations.
That said, I'd like to see a test suite that GPT-4 fails at, or struggles at, at least. And, it would save him a lot of time if he could get something automated together, it's clearly a lot of effort to hand test all those models.