i am playing since 2013 and finished over 5000 dungeon runs with my WHM and in all that time i used the tier 2 LB only once: it was in aurum vale last boss, there were no more fruits, we all had stacks, i was out of mana, everyone in the party was below 50% health and the next big aoe was incoming. so i hit the LB, wich healed us up before the aoe was hitting us and we survived.

tank LB is quite the same. i have seen tier 2 tank LB only 2 times, and it was both in the same situation: messed up dps check in haukke manor hard mode last boss.

i have never seen a usefull healer or tank tier 1 LB.