Two things that I've been told and/or read about torsion axles:
1. They provide a smoother ride and are better for critters.
2. Tires wear better (more evenly) with sprung axles.
Are either of those statements not true?
1. I'm not buying it.
2. Finding good trailer tires that consistently perform is a much bigger concern.
I literally run the wheels off my trailers loading them to their max.