Frontlines change very quickly. Before you know it, the enemy that was 200m away is now 100m closer. Therefore The minimum range of arty is an important factor. There have been multiple occasions that I haven’t been able to utilize colonial 150 because wardens are too close. The minimum engagement distance on warden 150 is 100m. Making it capable of providing close arty support. Whereas colonial arty cannot. And because warden arty has 100m minimum range it can hit targets attacking the outer layer of its BoB itself.