One shouldn't have to introduce rudder or elevator to perform a conventional axial roll. The roll rate would be fast enough where you couldn't provide rudder or elevator inputs fast enough. On a point roll (four point or six point) or a slow roll, to keep the appearance axial, you would have to apply small amounts of elevator or rudder with each orientation change to keep the aircraft tracking properly.

Generally speaking, any type of model that is not designed for aerobatics will require control inputs to compensate for aircraft elements that are ill-suited. A trainer for example, generally flies too slow, has a non-symmetrical wing (lift properties differ right-side-up versus inverted) and has significant dihedral for stability and self leveling characteristics. All of these factors work against performing an axial roll. Similarly, many WWII warbirds also have undesirable characteristics for precise aerobatic maneuvers. So, as a previous poster pointed out, the airplane and how it's set-up has a great deal to do with it.

In fact, a barrel roll is a hallmark characteristic of a warbird. They typically will dramatically change pitch when entering a roll, thus creating the barreling or spiraling effect. When you give the nose a pitch up before entering the roll (to counteract altitude loss during the roll), nothing looks cooler to me than a nice, long, slow barrel roll.

My point of view is, don't try to force an airplane to fly in a way that it wasn't designed for. It just makes things look awkward. If you want to do precise aerobatic maneuvers, buy an airplane designed for it. It still takes a good set of thumbs to execute the maneuvers clean and precise. Go to a pattern contest and you'll see guys who spend hundreds of hours a year trying to prefect loops, rolls and spins. Heck, they spend just as many hours working on flying straight and level as the origin of any good aerobatic maneuver is starting from a proper position and attitude in the air.