I use a red dot on the 45-70 guide gun for hunting in the thick swamps where shooting distances are probably 40yds on a good stand. Accuracy is good and is very quick.
On the .270 I have a Mueller 8.5-25x with red dot. The size of the dot in terms of MOA grow smaller with the zooming up to 25power. Small at 8.5, smaller at 25 due to the magnification of target. Mueller kept the MOA in mind when designing the scope and was my major concern for field shooting. This rifle is well matched with the scope in that it's dual purpose target/hunting....a nice compromise for coyote, varmints, deer, elk, what-have-you.