I agree. The Pinto and Pinto Rig Pulleys are nice, but they're not intended to be a substitute for an arborist block. I think the sling will be fine, if you keep the loads reasonable and you're not dropping them from above the anchor point.
I think you'd be surprised what it can handle. Bonner is a good one to talk to about this. I seem to remember a few years ago that he was pushing some limits with it to see how it handled.
Even though cheek plates provide some additional rope protection, it's still always important to take care when setting up a rigging system. You could still damage your rope with a block.
I guess I think the question shouldn't be if it's safe, but how can this tool be effectively used.
ive neg. rigged logs onto one a bunch of times. not like huge logs, but if i could let em run a lot ill use it. lighter than a block, i used it off a steel biner.
if i couldnt have stuff run a lot id step it up to something beefier, but i was really comfortable taking good size pieces on that pulley.
but i am speaking about it in past tense cause im a ring-er now