I 2nd this, minus Salesforce being hard to customize. It's probably too customizable.

At a certain stage of a company, sales reps expect Salesforce. So much so, that even when we finally caved and got it, I had reps specifically turn off Lightning and stick with Classic mode. It's like Bloomberg - it's what they know and can move fast in.

As much as it pains me to say this, it may make sense to have an option that can mirror the Salesforce UI vs reinventing the wheel. Or maybe even an integration / escape hatch to migrate everything off of Salesforce to this. Basically, if you want reps to adopt it, make it close as possible to what they know.