new guy, need some advice i/o card with custom variables

at long last I am at the point to start to build my own cockpit.

One thing I notice is that more and more developers start to use custom variables in switches (read Lvars) instead of using the default FSX variables.

With this in mind, can anybody give me advice on which I/O board to use so that I will not be limited to ONLY fsx variables. Most probably I will be fine with 95% of my switches using fsx variables but for the one or two planes that have custom variables I dont know how to continue.

I am about to just create a default turbine twin cockpit setup.

Any advice will be hugely appreciated.