Actually comparators are not the limiting factor, they do support over 5 bit (16 state) values, and can do comparing and subtraction with them, but its the redstone dust that limits signals to a max of 15, and even overwrites higher signals. repeaters and torches don't effect or change signals, but they will react to any signal over 0, and only output 15 when on. Not you need to overstack in order to see comparators reading and outputting higher value, or use command block success counts in order to "count" or set a value over 15. The only problem is you cant read those signals with Dust as talk about before, but you can use comparator subtraction in order to augment the signal down and then see the result.