Patrick,
As a SharePoint consultant we use both InfoPath and Pdf forms when comes to implementing solutions. Both technologies have their pros and cons. When working with customers, we work very hard to set proper expectations about InfoPath and other technologies. Praising easy-to-use InfoPath does not do any good to this technology. In my experience the most dissatisfied customers (Microsoft related projects) were ones who insisted on InfoPath implementation. As a software developer I can use equally easy InfoPath or VisualStudio. The problems come when business requirements are reviewed, InfoPath usually requires ะก#/VB.NET development. As a result solution becomes no different than any other C# custom project. However, customers still live with expectations that their business users will support solution later. As InfoPath MVP you should agree that such situations happen more often than we wish. I would agree that it is all about proper expectations and it should be handler on all levels: executive meetings, requirement review sessions, and even infopathdev forums.
As of your pdf forms assessment:
1. XML. Adobe LiveCycle Designer allows working with XML based data source without coding.
2. Web Service. Adobe LiveCycle Designer allows using data sources associated with web services
3. Pull data from SQL server. The same as above
4. Write data to SharePoint list. Yes. Actually many "yes". Adobe Acrobat X allows saving in SharePoint list. Adobe LiveCycle Designer allows using SharePoint web-services to upload document from any location. An integration 3rd party product (Pdf forms for SharePoint) allows bi-directional mapping of sharepoint columns to pdf fields.
Since I feel you might be skeptical to my claims, I include a link to Adobe Designer help: http://help.adobe.com/en_US/livecycle/9.0/designerHelp/index.htm?content=000546.html
I understand that it is an InfoPath forum. I believe in a balance view of every technology. InfoPath is a great tool when you have to implement forms fast and maintenance considerations are removed from equation. InfoPath is also good when you need a quick integration with SharePoint workflow (or even advanced 3rd party workflow tools like K2[blackpoint], Bamboo workflow, Nintex Workflow, etc).
P.S. I don't like smell of patchouli. I prefer basilic.