No experience with the ruderalis genotypes. I stay away from them, I don't like the effect.

If the plants have enough moisture in the soil, the humidity only effects how much water the plants use to transpire. (Not seedlings) You may see higher water use with the lower humidity...depending on the temperature as this also is a way for the plant to regulate it's temperature a little bit. You may note like a rippling on the ridges on the leaf edges. This is the first indication of stress, and usually is due to too much water...or not able to transpire due to high humidity....

People forget easily that effecting one parameter will affect several others. Minor, minimal changes with at least 3 days to observe the effect of whatever the change may be.

I have grown in Colorado, in the high country, in the winter (westslope). I kept the plants in the boiler room, which happened to have quite a bit of extra room, which most folks would not have.

Again the only time I try to keep high humidity is the clone tray and the seedling tray, both of which are covered.