The trade-off is the size of the valves and the slowness as compared to the non-compensating valves. The means of making that elite instrument playable is keeping the valves very very clean and very well-oiled. Many students will not keep the instrument clean enough to make technique as easy as it is on other instruments.
Since you are a euphonium player, make it a habit to play each "eupher" that is checked out to your kids so you can assess the level of upkeep the kids are practicing.
You might consider owning one fully compensating horn and the rest non-compensating 4 valves.