It really depends on your scenario but unfortunately I don't think that this will work very well - you'll be able to create it but it'll take a lot of time and the application won't have good responsiveness.
The layout of 2500 shapes won't be an issue but the routing of 10 000 edges will definitely be a big problem (especially in Silverlight). Also the initial load time of 12 000+ items will be a lot although there are a couple of customizations that can speed up this process.
In a summary - the biggest problem will be the routing and the sheer number of items.
I hope I was able to answer your question and if you need further assistance feel free to ask.
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