1)Radius increasing:
Turned on only Spirit Herb,Rampant Growth:

Turned on only Pereskia,Rampant Growth:

Turning on both:

Turned all Rampant Growths:

Problem: It's doesn't increase radius.

2)Speed of growing increasing:

If you activating Rampant Growth(Spirit Herb or Pereskia,or both of them),they increasing speed of growing crop(obviously,it's works like old Rampant Growth,with same particles,even if it's activated only one of them,even Cloud Berries doesn't change particles).So,there comparing of speed with,and without modifier.
Without modifier:

Only with Cloud Berry modifier:

With only Spirit Herb(only Pereskia or both or all of them,working same):

I think this should have been fixed in b6baf67, it was failing to recognise Cloud Berry as a radiuis modifier, and only increasing it by the base if a modifier was present, rather than increasing it for each modifier present.