Cruise will make them run very nicely at slow speeds. I've equipped so many with cruise for me and others that I've truly lost count. If cruise will fit, it goes in.
Note that the ERR cruise control will ONLY work for DC motored locomotives, no cruise with AC motors. I predict you'll be very happy with the ERR Cruise Commander performance.
If your TMCC locomotives are DC motored, you can add the ERR Cruise Commander M, which is a product for modular TMCC electronics without cruise. It's a very easy installation and gives you excellent cruise control for those as well.