Quorum

Quorum is a tricky and potentially dangerous topic. Too high and most proposals will fail because quorum is not met, too low and it presents an attack vector.

Solana has an unusually engaged validator community, however one must be wary of governance fatigue as well. This relates to the What and ensuring there aren't too frequent and trivial or excessively technical proposals that tire operators and ultimately lead to a decay in participation.

It will require some trial to observe a suitable number for a quorum, especially as participation is likely to be heightened initially before tapering off to a sustainable level.

A potential initial quorum number might be 50%, with a view of iterating quickly should this prove too high (rather start high and move lower than vice versa).

Another concept is not having a quorum at all and requiring a simple or super-majority of stake for all proposals to pass.

A simple majority might be sufficient for low-impact changes that might tune performance or make a small change accommodate future development, while a super-majority (2/3rds + 1) would be necessary for proposals impacting economics, consensus, the stake or vote programs, etc.