I originally bought the MA-T51-WH switch (no neutral) because it was a good looking countdown timer with increments up to 60 minutes as well as an always-on mode. I also liked the fact that it didn't require a neutral connection... until I installed it and found out that the lack of a neutral caused a problem.
I have a fan and fluorescent light which are connected to the switch, and when I pushed the switch, it would turn on for a moment then turn off for a second or two and then turn on again (and stay on). After contacting Lutron technical support (which is excellent), I learned that the lack of a neutral connection makes the switch less robust for certain types of loads. It probably works for most people, but since it didn't work for me, they recommended that I get the same model of switch that also has a neutral connection (MA-T51MN-WH). Since I have a neutral connection in my switch box, this wasn't a problem for me. The neutral connection did the trick and now the switch turns on as it should. One more thing that I learned is that the model without the neutral can have the two wire leads connected in either order, but once a switch with a neutral connection is added, the order of the live leads is very important. If they are connected in the wrong order, the switch won't work.
Now that I have the correct switch and all the wires connected correctly, it's working admirably. If you have a neutral connection in your switch box, you may want to play it safe and just get the switch with the neutral. It only costs a little bit more and could save you some trouble.