Here is my thoughts about this, for what its worth.
Before jumping into a new engine and specially those BIG one's, give it all a thought.
How long time did you spend learning current engine and the art pipeline that goes along with it.
If you are normal and not any kind of genius I guess at minimum a year. Moving into one of those
big dragons is not as easy as one could believe seeing the flashy advertisements. Plan for at least
one more year (probably more) to learn the new engine and to get things working again.
Then ask you'r self. Do I need to switch engine. What is it that motivates that?
If you are single developer or a small 2 man team I would recommend to stay with
what you have. The Big engines are to rich of features and possibilities to be handled by
such a small team if you as many of us only have some hours in the evening to work with the game.
This is of course not true for everyone, but I wanted to write down my thought about this as I have
been one of those "engine-switchers", spending years with switching to the new coolest thing and in
the end achieved nothing. Don't do that.
Think first, act then