Yes. The only honest and fair way to compare subs (and such nebulous concepts as "fast" vs "slow" etc) is in a very large space (eg an open field) when the influence of the room is minimised. Regarding positioning in a treated room, moving the subs by small amounts can indeed change the...
To me, the biggest issues are not the subs or drivers. If the room is not properly treated, moving a sub even by a few inches can make a dramatic difference to the sound. If the room is not properly treated, room resonances mask the actual sound emitting from the sub. If the subs are located...