1) Developer expertise with dundas object model is a big concern and blocking factor in speedy and efficient development. Your team would be able to make it but cannot guarantee efficient development and in case of an issue, it would always be a debate whether it's a limitation with product or developer bug.
2) Most of the visual components are based on Silverlight, and scripting would require development team to learn object model for the same.
3) SSRS already has got now Dundas chars and graphs, so just dashboard part of it makes sense for use.
4) Performance impact - You need to develop a few POCs to make out if these components dump out lot of html or huge images like what Infragistics does. Should not be the case as Silverlight is supposed to be a thin client support, but still its a question.
5) If these are planned to be shared over a tool like Sharepoint for collaboration, these components would be treated as just another ActiveX components. Also if you plan to use sharepoint, PPS is already a part of sharepoint 2010.
6) I cannot comment from a pricing point of view, but Dundas Dashboards would come more economic than Sharepoint 2010. Also both cannot be compared as both are totally different areas, and PPS cannot be extracted out from Sharepoint 2010 though this may be your only requirement.
Dundas may definitely win over pricing, but over a technical tug-of-war, the same cannot be guaranteed.