Finally got some time this evening to start on ARQ-1555. One of the main requirements here is to be able to dynamically proxy classes, rather than per class. Based on some feedback from Aslak, I made this happen by caching the class to be proxied when being invoked. This has an inherent issue in that it could be called in the wrong order, or concurrency issues, but I'll ignore those problems for now.
Basically, this should allow injection via @ArquillianResource @RestClient MyProxyInterface proxy; @RestClient can contain the contextRoot (or value), produces and consumes overrides. In addition, if you give @ArquillianResource a class that has the annotation @ApplicationPath in it, that will be used as the contextRoot. Let me know your thoughts, updating the tests for this new approach and backporting for RestEasy 2.x support are to come once I get some feedback from others.