Personally I can't live without r3 charge - even in PvE. But if you don't mind it, then getting r3 cleave is definitely worth it. You could also drop some Bash ranks to rank up your charge is you need to.
shinzeku wrote:...and the last Heavy hitter ruby instead of Energy flow.
To be honest, it's pretty easy to get 51 rubies, enabling you to get both the 3rd Heavy Hitter ruby and Energy Flow