From a purely practical viewpoint, I've come to favor canister stoves for younger Scouts (and inexperienced assistant leaders) for one reason: spilled fuel. Rookies, especially easily-distracted young boys, will overflow alcohol stoves (even a "legal" one like the Trangia), then light it where it sits. Likewise, they'll spill fuel when filling the cup on a white gas stove like the Whisperlite/Simmerlite, with the same explosive (though entertaining) results.

Sure, the only correct approach is to teach them the proper way to handle these stoves. But, with a bunch of rookies, they're usually not ready (or willing - short attention spans need work, too) for such things at first. So, without even knowing the Scouts had a policy on such things, I held off liquid-fuel stoves until the boys had a season or two under their belts - then I taught them how to work the other stoves.