The proxy generation tries hard to keep and clone attributes, but not on the constructor parameters. This causes problems for us, since our IoC container uses attributes to resolve certain values. When combining this with AOP proxying for e.g logging, we can no longer inspect the custom attributes on the resolved type, but instead have to use reflection to find the base class constructor.
Also, is there something that would prohibit keeping the parameter names? Convention based value injection could be nice, and that will also be tricky right now.