I know a guy that took a 300 footer (basically a factor 2 scenario) down the couloir. he came to a stop as his partner slammed into the only picket between them. They both walked away unscathed.
I heard mention of some old granite boulders (from the missoula floods) suitable for pebble wrestling in Tri-Cities. perhaps Sobo could enlighten us? I have not found anyone to substantiate that rumor though.
Banks has pebbles to pull. Vantage has a couple too.