When you say selectable for use, I hope you don't mean you have to actively select it on and off.
It also depends what sort of aircraft it is for.
I've used them on the 744 and 767 and they work well, and so far I've never heard any adverse comments from the Airbus guys either.
I'd have a close look at those systems, because, to be honest... they work, and I can't see too many reasons to fiddle with them.