In my experience, organisations grossly underestimate how much time they will need to spend working with their vendor.
Even once the platform is live, you’re still going to need to set aside several hours each week for upgrades, customisations, and fixes of your platform. Some organisations need 10 to 15 hours per week.
If you have a small team, this becomes a problem. Time which needs to be spent developing the community is instead spent developing the platform.
Once you move to an enterprise platform, you either need to invest in a bigger community team too or bring in more colleagues to help manage the vendor start of the process.