If so, you need SAP Universal ID. In a few months, SAP Universal ID will be the only option to login to SAP Community. Without it, you will lose your content and badges. If you have multiple accounts, use the Consolidation Tool to merge your content.
I am working now integrating RTC/RRC and PowerDesigner. And yes, its possible. But has to be with scripts via PD accessing IBM RTC REST APIs. You have to have the ability to read RDF xmls and create equivalents objects in the PD side.
Do these tools store metadata as RDF?
PoerDesigner can't import directly from those tools, but there are metadata 'bridges' available from metaintegration.net and Reischmann.com.
Also bear in mind that the DDL generated from a physcial model can be a "lowest common denominator" method of moving the model to PowerDesigner.