MCW
Somebody's talking crap here & it ain't the tree!
I live about 850m above sea level and regularly compete in events with some good mates on the nsw coastline.
Whilst I check my tuning once down there, I've never readjusted any of my saws.
Goin from high altitude to lower is not an issue, as the saws run richer on the coast, goin from low to high altitude is a problem if you go high enough I guess... 350' is no concern.
I find humidity will affect my own tuning more than the 850m altitude difference!
Just my 20 cents worth!!!
Wow. 850m? Can you even survive that high without an oxygen bottle? Can you see Jesus at that height?