I've just completed a Hen Long Panzer III with ElMod Electronics and battle system. I must say the system is REALLY good. Uses the same IR frequency as Tamiya but is much more configurable. You can also play around with the sound effects or even use your own.
I don't know if any other ElMod owners have tried this but I found that by leaving a slight gap (1-2mm) between the top and bottom of the commanders cupola, I could hide the ElMod 'apple' inside and still register hits without any apparent reduction in range compared to my Tamiya TBUs. I suppose it might have something to do with the ElMod 'apple' having 4 sensors arranged facing four ways. I'm trying to modify my Tamiya 'apples' now by adding extra sensors so I can hide them as well.

Here's a video link :-

http://uk.youtube.com/watch?v=3GDDcbEUeGU

Chris