Well, subduing a perp armed with a firearm with something non-lethal is, IMO, a risk I would rather not take. If the perp's firearm has more range and accuracy over my non-lethal weapon, then I'm at a disadvantage that I would rather avoid. I would definetely want superior weaponry on my side. Especially if the situation turns into a scenario where I am compelled to defend myself with deadly force without the means to do it.
Moreso, I think a perp would take more risks and be more bold knowing the only thing that's going to happen to him/her is getting bruised or shocked into submission.
I would prefer to use non-lethal force where possible, but I'd also like to know that in any given encounter, I'd have the upper hand WRT firepower and righteous cause. I don't like the idea of someone dying unnecessarily by my hand, nor do I think any sane person would with theirs, but if I'm ordered to subdue a perp with me being armed with a shotgun loaded with beanbags, then the perp had better be armed with something less efffective than that, preferrably a very noisy mouth and a teddy bear in each hand.