I have been playing with a new used Difalco controller and really like how you can plug in resistor networks to change the characteristics for different cars and tracks. With the controller I got the usual 148 ohm plus a 113 ohm and a 78 ohm. All linear. I got a custom kit and made up a 7x3.9 ohm, 7x3.0 ohm and 15 2.2 ohm for a total of 81.3.
We run a run what ya brung with the only restriction being a Hawk cobalt motor on a Hasse king. I had been running the 78 ohm but find the new custom really helps in the gutters with the sensitivity turned up maybe to 5 or so.