I haven't seen the modern top ui, but it sounds useful and I'd be in favor of it if it doesn't break things.
But I have to note that terminal emulators and coloring curses applications is very hard to do in a way that works across everyone's favorite color scheme. It's bound to result in invisible elements or missing contrast when you use too much coloring. It's not a fault of the designer but the ways terminal emulators work (in other words are limited). So by all means, if it doesn't break anything, enable modern top, but use caution with colors.