I just started with RS for a few pro works and it is very fast, especially preview in realtime for your materials and light. Render time is halved. (2k rendered scenes in 12 mins instead of 1 hour! a shop model with 32 area lights on the ceiling)
I have a 8086 intel @4.5ghz/ 32 gb ram + 2 x 1070 ti's.
I used Vray a few years and do get back to it when I have more materials I need that are already Vray and the scene is simple.
Vray renders the light more nicely, I think it's the physical GI that is better and has more shades/hues.
Increasing bounces in RS doesn't make a big difference I think.
But I have only been on RS a few month so it can be fine tuned still.