​Do you think the Neo-Volkite is better and more viable on Lethal since the latest 5.0 Patch?

It is barely "better and more viable" on ruthless. Maybe if the target lock worked it would be good but currently target lock does not work when moving (character's arm is moved off-target if I move my camera as if I were using aim as opposed to target lock) giving it a more generous weakspot hit-detection would help the weapon a lot. The actual damage it deals is good but it needs too much time on target while getting swarmed/shot at to be viable on anything but -thropes and stuck carnifexes.

It's a really good weapon on lethal for those that it is available for.  On assault heavy bolt pistol is great if you are good at headshots and probably better overall but neo has its place.  It is great against zoanthropes and terminus enemies.  Even better if there are more than one on a team and they focus.  It also has pinpoint accuracy from hip fire.  It's perfect for doing ranged damage and still being fully aware of your surroundings at the same time.  It's also like one big laser pointer in the sky for your teammates to know exactly what you are doing with it.