Get the ADA new amazonia, suppose to be last longer. My personal opinion, ADA soil still the best soil for planted tank.
Regardless what soil brand you use, HC will float by itself after a while. this is happen if the HC grow so thick until the bottom part does not receive light. The bottom part will start to rot and the root of the top part unable to reach the substrate. You might be able to delay it by frequent trimming.
You need to worry about fertilizer instead of mud. It wont suddenly turn to mud unless you frequently disturb the soil.