I've played around with thumbless on bench press, and used it for awhile a few years ago. Mentally I can't make myself do it anymore, for the safety reasons mentioned. If I had a good spotter everytime I lifted, I might use it, but I worry about the lift-off portion of the lift with a thumbless grip. I have enough trouble getting random spotters to lift me off to the right spot.
I have also approached the grip similarly to spidey in the past 6 months or so. I've played around with different rotational positions in my palm in an effort to engage different muscle groups more effectively.
Thumbless is pretty much my natural grip for pullups. I prefer it. I deadlift mixed grip.... with thumbs.