My $0.02 worth.... if the projectiles has "sufficient" energy at the range I'm shooting it, and it's legal at my location, then I'm fine with it. But that being said, it does depend on the projectile. I have hunted deer with CF rifle, smoothbore shotgun (slugs), rifled shotgun, and muzzle loaders (and crossbow, and compound bow but lets ignore archery).
I'm all for the 1000 ft/lb (or close enough... 900+). But, here in Ontario, someone could use a 223 Remington for deer. I wouldn't. It may have 1000 ft/lb of energy, but a 55gr or 62gr projectile at 3000 ft/s (or whatever) may not (IMHO) provide sufficient expansion/penetration so I personally think it would be unethical to shoot a deer with one. Same as 220 Swift or other 22 caliber centerfires. Legal (in Ontario). But I wouldn't. 243 Winchester? With 100gr soft point projectile no problem. Maybe not moose, but legal here and I'm sure I have read on CGN many people using 243 on moose (hey, it's almost 2000 ft/lb of energy at the muzzle).
I also feel that it is unethical to shoot large game (deer, etc) with a FMJ projectile. AFAIK, it is legal to do so in Ontario. I never would.
So, 20g sabot for deer, moose, bear? All legal in Ontario and I would do so. At 300 yards? Nope. At 50 yards? For sure.