I kinda think that implementing back the broken RT would be a better solution than not having anything. Just put a giant label "Unstable Use at own risk", and let people play with it.
I support this idea and add that then you leave it like that and direct your energy and resources to matters that are more important ;)
Or is this something your future paying customers honestly want? I never saw the benefits with Vray RT and Octane, other than buying Octane in 2010 because it was a "nice, cheap toy". Never used either of those implementations with real, paying projects.
I my self was once working for a company that made fireplaces, I was making quite a lot of interiors for them there was a lot of tricky surfaces to expose aswell as some ocasional imperfections using RT, I was able to set the light exacly as I waned way faster than render-move style. Its a huge time saver for those that work on crative packshots etc. RT is not my #1, but it surely helps especialy when you are designing something with someone like my new boss, she knows nothing about the program and gets a bit iritated when I need to render-more-click-render-more-render.. anyway its a nice tool.
Well I agree with the render/cancel/change settings/render/cancel/change settings -perspective.. kind of.
I think if you (not you specifically!) have a hard time getting materials to look right you're overcomplicating the process somehow and the issue lies in the user and no amount of real-time rendering will solve that. Then there's the part about setting a product shot to look right. Well, sure, but nowadays you can already accurately see the exact direction the shadows of your lights go when setting them in the viewport. As for rendering said environment, what else do you need? surely it doesn't take much time to do a test render and see what's up.
Also last I used any of those implementations there were a lot of issues such as long waiting times - or even having to restart the RT engine - when merging in new objects or doing something else the engine disliked. It just seems like a gimmick to me still and I hope it's left alone as long as it takes time off of getting the core elements right.