+P+ was loaded for LO with the understanding that firearms makers were not responsible. The understanding is that the guns will not blow up but accellerated wear will definately result.
It's only value is in guns wgich were not offered in 357, so was obsoleted with the advent of J frame 357s. If one were undercover, I guess I'd risk wearing out my chiefs.

On the practice range, I would treat them as mid-range 357s. Use limited amounts in K frames, or use them in N frames.
Russ