Box mags are no different to having a normal hopper, so should be restricted in a game scenario to only a certain number allowed on the field.
Where a heavy gunner is required then am individual site/event can decide if a heavy gunner could use something like a Q Loade, or even a normal hopperr.
The normal point is limited ammo/reload, so I'd say Q Loaders are out as general use.
To me the focus is more on limited shots, having to reload frequently and play more tactically. Slow the game down so you have to think about your shots and the consequences of being vulnerable during a reload.
Some others see it as pure magfed, but I think if it's a format that wants to grow then it needs to allow people to try it with kit they might already have and feel comfortable with. There are always magfed loan markers available, and people should be encouraged to try them, but some people aren't comfortable with using other peoples kit.
I do think that someone running a stick feed will maybe be disadvantaged against someone with proper mags, so if the playing style appeals to them enough to play more often then they would probably end up looking at a proper magfed marker of some sort.
It's just another style of game and it's good that people will have a choice of different styles to play. Not every baller only chooses one style. Some play across all genres, tournament, scenario, magfed, milsim. It's all paintball.