I think the bosses are a bit uneven and there is quite a bit of RNG involved as well. Boss with electrified floor can tax a healer if other people are not overgeared, especially the tank. Desert storm boss is quite easy on a shadow (force speed), but guardians have quite tight situational awareness check and if they fail it it's basically a wipe (if not very overgeared).
never had any problem on my Guardian.
30% speed boost for the full Duration of the Sandstorm is great.
better then the +30% for 6sec Hold the line Vanguards have and equal to Shadows +150% for 2sec Force Speed.
and I never even tried to friendly jump, never had to.
though I don't have a 55 Vanguard so i don't know if they are as bad off as they look it's easy for Shadows and Guardians, if they are awake and have read their Skill tree (many don't).