Risks associated to using a webhook to send new lead records to CRM (MS Dynamics)
We are in the process of optimizing our current purposeful duplicates process. Rather than create the duplicate in Marketo via a webhook (and then sync the lead to CRM), we would like to bypass the creation of the lead in Marketo and create it directly in CRM via a webhook.
As you probably know, passwords are stored as plain-text within the Admin area of Marketo:

It's been suggested that we setup S2S (server-to-server) authentication (client ID and token). This would provide a more secure approach than just using the webhook with a userid and password. Also, S2S accounts cannot be used for logging into CRM through the UI, it is programmatic use only - so if something needs to be stored in plain text then S2S account is a better candidate than an actual account. The risk is not eliminated completely but is minimized greatly since the account will only have access only on leads and that too in a time bound manner, we have the control of changing/deleting a S2S account from our system more than we have control with a normal account.
We have very strict data security guidelines in place. So while the risks may be minimal, the team is still hesitant in moving forward with this solution. I'd be interested to hear from others that have experience with webhooks and this sort of authentication. Are the concerns that our team has legitimate?
@Sanford Whiteman, @Paul Wilson