I don't meant to be a complete bean counter but if all Slack can point to as a benefit is a "certain sense of community" even among a group that cares a lot about tools then it isn't it a great spot.

Is your revenue down since switching to Teams? Sales volume? Number of bugs fixed per release? Onboarding new hires slower? Time to fix critical incidents up?

Those are the kind of things I would have expected you to mention if there were actually a massive difference between Teams and Slack.