For your consideration...
I've taken the liberty of writing a style guideline for American Black Ale. To give credit where due, I consulted the OP for a basic idea of the intended style.
Maybe someone will post a poll comparing the two style descriptions?
AMERICAN BLACK ALE
Aroma: prominent hop aromas emphasize floral, citrus, and pine from traditional American hop varieties. Citrusy hop aroma is common but not required. Sweet malt character compliments hops, This style should present hints of roast, toast, and optionally, chocolate malt. Dry hopped character is often present. No diacetyl, notable fruity esters are inappropriate for this style.
Appearance: Dark brown to black, tan or white head.
Flavor: A balance between pine and spice hop flavors, with optional citrus, grassy or floral notes present but subdued. Mild to moderate bitterness associated with caramel, roast, and/or chocolate malts compliments hop flavor. Mild roast flavors should not detract from the hop emphasis. Roasted, burnt, or ashy, flavor is not appropriate. Caramel sweetness, if present, should be very mild and subdued, and should not detract from a dry finish. Diacetyl is inappropriate. Emphasis is on hop flavor, complimented but not overpowered by bitter, roast and sweet hints.
Mouthfeel: Light to medium, with prominent bitterness from both hops and roast malts creating dry mouthfeel. Optionally, resinous character associated with dry hopping compliments pine and spice aroma and flavor.
Overall Impression: A heavily hopped, light to medium bodied dark ale. Strong hop presence mimics an American IPA. American dark ale is not as full-bodied or malty as other common varieties or beer that are this dark. Strong hop bitterness and muted roast or caramel malt presence are more similar to IPA than strong ale, porter, or stouts. Taster should come away with an impression of a lighter and drier than expected, refreshing, hoppy beer.
History: A style originating in the American northeast in the late 20th century, it came to prominence on the Northwest coast of America in the early 21st century.
Comments: To reduce roast bitterness, some brewers cold-steep dark grains. Alternatively, darker grains may be added at the end of the mash to incorporate dark color with minimal roast bitterness. The emphasis is on IPA type base flavor and aroma, with nuances of caramel and roast malt adding, rather than overpowering the base style.
Ingredients: Pale or pilsner malt, medium caramel malt (20-80L) may be used in small quantities. Roasted malts are necessary, and often de-bittered black malts are used. American hop varieties, especially those grown in the pacific northwest, or hops with similar pine, spice and floral character are used for bittering and flavor. Dry-hopping is common.
IBUs 50-90+
Color: 25-40+ SRM
OG: 1.050-1.075
FG: 1.008-1.016