The whole Linkedin lead gen connection is a mess and from my support tickets with Microsoft it seemed that not many people were using it. I hope that after the big real time customer journey updates Microsoft has more time to fix the integrations.
1. It creates new leads / contacts for all active campaigns without matching with your current database (so be aware that it might create a bunch of duplicates / create hundreds of contacts when you activate the sync for every user. Test this in dev first).
2. Everything gets assigned to 'system'. There is no way to assign it to teams/users like with normal landing page forms (have to create workflows/flows for this). This might be an issue depending on your environment/security roles.
3. It wouldn't work with custom business process flows (supposedly fixed, but haven't been able to test that yet).
4. Fields don't sync correctly (email was for example not transferred to dynamics unless they had their email public. This means you could see the email in the submission/export, but it wouldn't transfer to dynamics making it pretty useless for marketing campaigns. Don't know if this is fixed yet).
5. field mapping limitations like you mentioned.
Anyways, this is just a small portion of the issues I've had with this functionality and my contact with Microsoft. Due to all these limitations we are currently not using it. I understand that this is not a very useful reaction, but it's just a caution.
