I think only elite players are going to be somewhat uncapped in that spot. It's very easy to miss 4bets with some low suited hands especially when deeper even for reasonably strong players, therefore OOP is going to have a significant advantage on flush runouts.

Both small bet (around 30%) and 50% pot, setting up a river jam are viable strategies and can perform better according to how IP is building their checking back range. If they include reasonably decent hands / strong backdoors 50% and a more polarized approach is going to perform better, otherwise, if you expect them to fold too much 30% or similar is going to accomplish the same task for a smaller investment.