At what point would you step up to ferrea hollow stem valves

Controlling the valve mass is the spring's ONLY job, the lobes are effectively trying to "throw" the valve into space. The higher the velocity(& remember energy is a square law- 2x speed=4x energy) and the higher the spring load & the frequency tuning has to be. Velocity can be different to the extreme for the same lift so, no........less valve mass means one can use a more aggressive cam on the same springs, or use less spring load on the same cam, with a good beehive offering the best of the latter....
Yeah, but the valves also have gravity on their side. I think some of yall are over thinkin this stuff. There's just no way in hell I'd run a hollow valve. I think it's splittin hairs and it's best to look elsewhere for "upgrades".