I have and use both the MT14A and the MT13A.
I like both however the newer MT14A does have a better viewing angle/range and better X10 transmission.
I don't use either for timers as I have a PC running 24/7 with a cm15a connected so timers are handled with it.
I did setup a few timers on both initialy and both perform the tasks well.
The MT14A which replaced the MT13A and almost identical to it.
The differences are:
1: The wallwart though the old MT13A wallwart will work with the newer unit.
It is much larger and heavyer and since this handles the X10 PLC sends the new unit sends a much stronger X10 signal.
2: The display though the size is the same thats where the simularities end.
I found the viewing angle on the MT13A to be very narrow and you had to be higher then it to actualy be able to read it.(maybe just my unit)
Placing the MT13A on a bed side table made it hard to read in bed Unless you sat up.
The MT14A display I can read from just about any angle and from the other side of the room.
The Mt14A display is brighter which is the one thing I dislike about it. I suggested a dim button be added when ever a new version is created.
The mini timer is just that.
The only thing that isn't smaller then the original X10 timers is the display size however they've cramed more info into it.
I'm not a big fan of alarm clocks but the fact these can turn on a light or any X10 module, the way it wakes you up is only limited by your imagination.
Is replacing your existing MT13 with the MT14 worth it?
I say no, if your MT13A is still working.
If your wanting better X10 signal strength a repeater may be the better route.
Is it worth picking up one of these if you don't have a mini timer?
For me I'd rather put an extra $35 towards a CM15A and have the option for 256 addresses to add timers to then the limited 8 of this.
I also have too many clocks now as it is.