Since I mentioned Sterling speakers, I'll reply. Alan Shaw has publicly said that the differences between some Harbeth models (specifically 30.1 and C7ES3) isn't worth spending to money to change between them, and anyone worrying about it may be better donating the difference to charity.
It's also frequently said on the heavily moderated Harbeth forum that all you really need to do is pick whichever Harbeth model is the right size for your room.
So you can disagree that different Harbeth models are similar if you like, but there are plenty of people who'd say that the similarities far outweigh any differences.
And with Sterling, Graham etc, they don't just share some design features, they're all explicitly refinements of the same designs. The OP was looking for recommendations, not for other things that sound exactly like 30.1s, and specifically mentioned Spendors. So mentioning the other brands is entirely relevant.