Its pretty much gimp or better depending how you look at it.
It may seem just like 1mp/3secs, but its really useful for keeping mp up, I have never run out of mp main healing, nuking, debuffing,buffing,etc.
Its really for keeping the chain alive and 4mp/tic is pretty nice, not much you can get from /smn sub but aerial armor but most melee sub shadows so sort of a waste.
/blm more ways to debuff and tractor and escape more well rounded that gives more abilities
But /smn for rdm is for really just mp recovery and keeping the chain alive.