I'll even disagree with that, too. I think the DD-20's analog sim is pretty durned good. Good enough that I was able to fool someone into thinking a recording I did was done with a real analog.
I was not saying it wasn't any good. But I wasn't impressed with it.
Maybe I looked more at the other features of the DD-20.
(And I am not a fan of the DM-2 anyway

)
IMO the DL-4 has more on the menu when it comes to modelling... that's what I meant with "if you're into that".
I do not own the DD-20, just tested it for about 20 minutes in a store.
I do own the RE-20 and the Line 6 DL-4.
IMO the DL-4 is very good at the modelling... of the Echoplex delays and the Space Echo.
Well, I don't know if the modelling is accurate, since I am not familiar with those vintage units for real, but I think the sound quality is very good.
I like the Space Echo model more on the DL-4 than on the RE-20.
RE-20 is not bad either, easier to dial in. But it's a bit more "reverby" IME and I don't like that.
Maybe the RE-20 is better at actually replicating the Space Echo... but my ears like the DL-4 a bit more.
It's all what you expect of it and how it sounds to your own ears.
Knowing what I know now, I'd never buy the DL-4 and RE-20, but the DD-20 instead. But.... because I want to use it as a digital delay with different presets.
I like analog delay too, but for that EHX is my choice.