I gotta say, WLP820 sounds like a real loser strain from all accounts I have seen.
I just did a Dortmunder Export with 833 and it went from 1.055 to 1.008, despite mashing at 68. Eating that maltotriose, I guess.
WLP833 is my other favorite lager yeast. Actually I can't decide which one I like better, that one or 2206. Both great.