I see it as more of a foreign export stout style with perhaps a lager yeast to keep the fermentation profile fairly clean.
Good call - it's pretty much a foreign export.
Actually per BJCP:
Characteristic Ingredients: Similar to a sweet stout, but with more gravity. Pale and dark roasted malts and grains. Hops mostly for bitterness. May use adjuncts and sugar to boost gravity. Typically made with warm-fermented lager yeast.
Style Comparison: Tastes like a scaled-up sweet stout with higher fruitiness. Similar to some Imperial Stouts without the high bitterness, strong/burnt roastiness, and late hops, and with lower alcohol. Much more sweet and less hoppy than American Stouts. Much sweeter and less bitter than the similar-gravity Export Stouts.
I just haven't seen much written on this style....