[phillc73]

It's not so much a problem of the yeast and attenuation. Nottingham should be fine up to 14% and for a high gravity beer somewhere above 75% attenuation.

The issue is yield and lautering. The mash is so thick, or rather there's so much of it, that proceses need to be adjusted to account for that, and from experience yields are much lower in a typical entry level craft brewing system (400L).