Trailing delays are awesome! I know the Line 6 DL-4 isn't on the same sort of level as the Moog delay but I love using the filter delays with repeats on high so you have this funky soundscape that trails on after the pedal is turned off. I say go for it!
I really want that delay but my god it's pricey. I think I want one of those more than I want their LPF.