I emailed Schliecher about this. Here's the response I received:

"Here are a few short suggestions. The payload of the ASW 19 is 75-115 KG. The weight of the non-lifting parts must not exceed 225 KG.
The maximum take-off weight of 408 kg must not be exceeded with or without water.
Greetings from Poppenhausen"

Sounds to me like they don't know anything about 805 pounds either. In the end, we will probably pass on ASW-19s. 805 pounds limits the maximum pilot weight of them too much and I don't want to risk having to convince someone to willfully ignore the TCDS while doing a weight and balance.

That said, anyone know of a good Discus B for sale in the Western US?