With 60 RPG no one is going to be hosing in it for long, what's that about 6 seconds worth?
Compared to a Hurricane Mk IIC the Whirlwind is about 20 mph faster, has much better all-round visibility, better gun placement but only 2/3 the ammo. Its also got about a 10% better power loading which should help climb rate but with flaps-in a 25% worse wing loading. With the Fowler flaps out it increases the wing area enough so that the Whirlwind would then have only about a 15% worse wing loading. Fowler flaps should help the low speed lift more than by just increasing wing area but by how much is anybody's guess.
So I reckon it would a slightly faster, better climbing, maybe slightly worse turning Hurri IIC that you can see out of but with a short clip and not much range. An interesting plane and probably not an MA hangar queen but its not going to get everyone out of their P-51s.