I understand we are all talking panel lines but I have to first say that your build is fantastic!
Getting back to your initial question of better "with or without" panel lines, I say absolutely better! Especially after your second wash with some body color toning it down a bit.
In my opinion, just about all builds should include some sort of wash or darker tone in the recessed areas to depict what anyone would see on a 1:1 vehicle. I am certain there are many ways to establish this and that is why this forum is great for most of us trying to learn. I am currently trying to perfect my own technique as well and using everyone's thoughts and methods here is very helpful. I tend to lean more towards the softer tones than the bold dark black lines. Just my opinion and taste but I base my premise on "less is more". Sometimes not all panels need to be darkened very much. I find that deeper lines are better than darker lines.
Chris