When running a delete flow step, if one adds a choice to it, this is what it looks like :
It seem, based on what's written, that the choice will give you the possibility to remove the lead from SFDC or not, but that the lead will always be deleted.
But this is not true: actually, the "do nothing" just do not delete the lead from Marketo. If you want to delete the lead from Marketo but not from SFDC, you have to select "false".
Although it's consistent with "do nothing" in other flow steps, it is really misleading and probably a bit dangerous, although it will not drive you to inadvertently delete a lead. So I wanted to warn the community about this.
I tried already when setting up this Feeding the Durable Unsubscribe List without increasing the database , and tried again after Josh's question on this blog article.