I tried to look for a link for the Galerian Crossfire mod, but both google drive links are giving me issues. Would you happen to have an updated link or better yet upload them to mediafire or a different site?
Haven't played VC4 yet, but in 2 and 3 the AT snipers are valanced pretty well against regular lancers. Actual Lancers have more ammo, do more damage and resist interception fire better. So you'd prefer them for taking out tanks at close range. The AT snipers are good for taking out towers and turrets, since they can target the sides and back without it auto-rotating. Also sometimes good at taking out tanks in a solid defensive position if you can get a good angle on them to hit the radiator.