I’ve owned a lot of high end delay pedals including a Timeline, El Capistan and an H9. I replaced them with a DD-500 when it came out and haven’t had any regrets.
The Timeline sounded amazing, but there’s “baked in” modulation on a lot of the algorithms that sounds a bit artificial for my taste. I prefer the “cleaner” — or maybe slightly more raw — base sound of the BOSS and lots of control over modulation via the ASSIGN slots.
The El Capistan is still my favorite tape-only delay pedal and I actually still have one. It’s really musical and the interface is dead simple. But the space echo algorithm on the DD-500 is in the same league and it’s more convenient (presets, separate L/R ins and outs) so I rarely the El Capistan any more.
Th H9 is brilliant but I didn’t love the delays and I’d rather have multiple effects boxes to run simultaneously at a lower price than multiple H9’s.
I think BOSS really killed it with the DD-500 (and the entire 500 series). It sounds fantastic, has a ton of modulation options, the LCD makes on-pedal editing pretty easy, it has full MIDI support, it can play two delays at the same time and it’s cheaper than most of the competition. It’s to find any faults with it as long as you like the sound of the algorithms.