I spent an hour doing a bit of A/B. Used Azla tips on both. Both fit well, the MKii feel better than last year from a fit perspective.
My thoughts for now is that they are far apart from a tuning perspective and elements to work with. The bass on MKii is of different magnitude and impact than RSV. The rumble that comes in with for example Kill Jill by Big boi around 0.36 secs feels impressive vs RSV. Also in hearing something like Tears for Fears Shout and the riff during the last minute of so is clearer and deeper on MKii vs RSV
However I did decide to stop comparing as I did not see point
Listening this morning to some Spotify with my RSV while making coffee, just brought me back to my senses, the RSV is awesome at it's weight class and the MKii is awesome as it weight class, sorry seemed like a stupid conclusion but when I did the A/B human biases took over

If you can have both, buy them both as they are great on their own merits. I know everyone will find something to criticize but I think finding perfection is just a mind trick. Both of the IEM's can really give you a variety on the tuning that will let you switch them around and feel satisfied with both
Physically both IEMs feel close for me , so did not have any insertion issue. When compared with Earsonics Purple both RSV and MKii look like a truck .The ES Purple have their own sound merits, but the size make these so easy to use everywhere
Sorry very high level comments and was concerned on creating merits of one vs the other one