It's been said before, but it bears repeating, you don't koshi a 300lb gorilla the same way you koshi a dainty 100lb lady.
I guess I have a different experience with aikido. Especially koshi waza. I do koshi waza with 100 pounders the same as 300 pounders (like all waza). The uke provides all of the energy necessary.
The energy the uke is putting out is what they either absorb or redirect with their ukemi. All you need to do with any waza is "entice the uke into putting themselves into a position where gravity makes it impossible for them to regain their posture and they have to fall.
300 pounders fall like 300 pounders and 100 pounders fall like 100 pounders. Sex of the uke has nothing to do with it. Ability and experience is the determining factor in how much speed and intensity is used when we practice with anyone.