In the big picture, drum switches can be rated to handle more current for one thing, and another is the number of "poles", or actual separate switches inside. I don't think I have seen a triple pole single or double throw toggle. Not saying they don't exist, but I just haven't seen them, but in drum switches, the extra pole switching is simple as stacking more wafers in and adding contacts.
One other thing just crossed my mind. Some double throw switches have a safety feature to prevent flipping across the off position and going straight from forward to reverse. Not all, but a really good idea. That's a feature I haven't seen on a toggle switch either. I have seen it on a few drum switches though.
All things considered, if you find a switch rated for the load you have, and it has the poles and throws you need, then the only thing I can think of MIGHT be duty rating. I would expect a drum switch to outlive several toggle switches.