How would you compare the severity of your LO's 4 month and 9 month regressions, if they went through them?

For us, the 4 month regression was horrendous and at 9 months she seems to be having trouble with her naps but her night sleep has been unaffected (knock on wood).

I've heard the 9 month regression tends to be worse so I'm bracing myself. Anyone care to share their experience?