Hi Benny i like to test new things i have tried alot of renders but this a complex answer for me.
I have not switched to Corona from Vray, i still like vray for other kind of work where is more stronger than corona maybe not many people know but im now fully working as character artist and vray skinshader is my favorite and im waiting for the Alasurface arnold skinshader from vray, i wish 1.6 have skinshader comparable to this or even better so i can switch to corona in one of my upcoming personal projects.
3.4 is as easier as corona to setup so your friends are right , i tested vray in this scene as you know vray is know for its speed but in this scene corona was x2 faster and cleaner it looks like a simple teapot scene, vray beat corona in speed but as soon you scene have alot of materials and complexity corona takes the lead and i really like the corona glass it is just too good .
Vray got stuck in glass shaders and metals to even create a comparable glass in vray you need to add more than 5 ray depth for both reflections and refractions if you put something like 20 it will take even 8 times more time than corona to render them.
There is another stranger point but this scene in vray, corona showed alot of highlights where vray did not, im not sure why it should reflect the same things and i really make sure every setting was correct for both to work the same but corona showed better highlights reflections where vray capped them in someway.
what i like the most from corona is the speed, the ''peace of mind'' that you focus on artistic things more than settings the glass shader and the extra highlights i can obtain, what i do not like is the removal of the bucket engine.... i rendered all these images using 1.3 bucket it was also better for preview since it has somekind of AA while the progressive you need to wait more to have a decent AA to see the general shape better maybe im wrong since i have used buckets for so much time.
The most important for me are the developers when i read post or forums i see alot of positive energy in them this for me is a positive trait in any person and im sure this is the most important one as they have passion for their product and user base.
another thing i do not like was the removal of the ''low thread priority'' this is why i used 1.3 too ,this scene is big and ram intensive so it used more than my system had and 1.4 parsing times where even 1 hour vs 1.3 4min.
this is a personal one but the ''filmic'' tone mapping for me is a wrong step for Corona, Fstorm got a correct tone mapping almost identical to a camera what is lacking now is the camera responses like what octane have.
stuff i think is missing is a skin shader like arnold and alasurface non energy loss shader , i hope Ondra read this and take in consideration this skin shader since is the best one at the moment.