Jonny,
I was shooting with the Nikon D70 until this last week. I don't know the specs on the buffer, but I never had a problem. When I first started with the D70 I would fire off 10-20 shots? Many were redundant. I was having fun shooting in continuous mode knowing I didn't have to pay for the development of 400 images--my main reason fo selling thee F100 and going digital. Lately, I've been shooting shorter burst as you mentioned you do. I'm getting better at anticipating what's going to happen next and fire.
I should have the 20D and 70-200mm f/2.8L USM Monday. Shooting a game Tuesday night. I changed my mine about the 85mm 1.8 for now, as I was hunting for a 35mm 1.4L. While I'm waiting for that lens to become available I'm buying the 24-70mm 2.8L USM. Should arrive Tuesday. Can't wait to shoot with the new gear.
Bill