Vital is a very powerful synth indeed, just as Serum, which the dev obviously took some (a lot of?) inspiration from.
In direct comparison however, Vital wins for its better workflow / GUI layout. Drag&Drop for connecting modulation source + destination is nothing groundbrakingly new, but having a mouse-over preview whilst dragging a source over different destinations, for me is. it’s a powerhouse of inspirational source and invites everyone to go on sound-design discovery with an unsurpassed ease of use. i never felt so deeply rooted with a softsynth before 
Vital is rather light / moderate on the CPU… even with higher unison.
the 18 instances never sound at the same time. 4 instances were used for creating the speech for example.
the problem in renoise is however, that they do not idle / auto-suspend correctly, so they are either all active in the background and use CPU or if you force the auto-suspend, their reverb and/or delay tails will get cut off.
because of that, i have had to switch to draft quality for some instances whilst working on the track.
so true. i am actually very melancholic about the passing of time and how everything decays. so don’t get me started 
Thanks for your comment !