Hopefully the valve seals would benefit from HM oils as well and the
front and rear crank seals.
I've used high mileage oils from Pennzoil, Castrol, Mobil 1, and Valvoline for the past 30k miles. In that time, the puff of blue smoke on startup from weak valve seals has gone from significant down to almost non-existent. When I had the intake manifold off this spring I could see a tiny bit of oil seeping down the valve stems, but apparently that's not enough to make any visible smoke when it fires up. I did have a rear cam seal start to weep this winter, but that may have been previously weakened when the pcv system failed and pressurized the crankcase a few years back. I know it puked oil from the top end when that happened.
Don't have good data on overall oil consumption with HM vs non-HM since the car had slow leaks of various nature from hoses and places other than seals up until this year when I fixed the last of the problems. This oci it's using about 1 quart in 5k miles.