[jstandard]

Having looked into doing a very similar migration, I generally agree with you. There are performance, control, and speed gains on the back end to be sure. It's replicating the flexible, intuitive UI where the cost argument always breaks down.

That last part is the most important. It's why you're really using Mixpanel/Amplitude/other vendors. To say "we replaced Mixpanel" without addressing the front end feels a bit disingenuous to me.