I've evaluated both of them from a user's perspective. I am a developer who has expericence with Silk Performancer.
Here are my opinions in summary.
- It should provide a higher level API than writing Jython. Silk Performance BDL has a better design on this although it's somehow akward Pascal syntax. IMHO, Jython can be used to parse and eval the higher level API easily, I did this myself for writing a mini command line processor in my project, it can turn a cmd,A1...An into a function call (API) of cmd(*args). pretty cool. 1 liner of lamba function.
It looks like Proxy server is very popular in implemening this technique.
The recorder 's proxy can be improved to support HTTPS. Only 1 certificate needed to install btw the browser and the proxy server for Java solution.
Silk did better job to bypass SSL layer i think. pretty cool too.
The GUI is sluggish written in SWING. should use IE/browser or rich client in SWT.