Just make sure that if you use iRule that "Repeat on Hold" will work on your device. It doesn't on my Sony Xperia Tablet Z and is a major pain for things like volume control. Their support is pretty bad for the android version.
look toward touchsquid. support is good / responsive. cost is ok. If the s4 a has built in IR, then it works. Of course, this assumes that they have caught up with a new release with support for this model... they have been pretty good at getting up to date pretty quick.