I like CR EV a lot. I have made some pretty big /complex tree's and it's hard to say how accurate their EV estimates are for complex trees. But it is interesting having the ability to run some scenarios over and over again, and just see how often you'll flow down a certain path given certain requirements.

Like if you knew on a certain board, you would ck back flop in certain conditions and call turn leads, to see how often that happens and how often you are actually calling. Or just other generic type spots where it's hard to really know frequencies without running some monte carlo simulation.

It's steep though at $100. I don't think it should be necessary at all at lower stakes, but it does make GTO studying easier.