I am a frequent user of RT, and run the development version. I like to follow the development as it happens, and contribute with a bug report now and then.
If I was a professional with high production I would use lightroom because it is smoother to work with and more "fool proof". For fine art production I would possibly use RT anyway, because it has very competent algorithms and gives the power to the user, power to mess things up too. One example is to provide several highlight reconstruction algorithms, which works best depends on the photo, picking the right can give splendid results, the wrong can ruin the picture which you may not detect if you don't inspect the picture thoroughly.
Another advantage of using RT is artistic integrity, you can always find out exactly what an algorithm does, so you feel that you are in total control, there is no "make picture better in some secret way" type of functions.