yeah you obviously play good and evil or atleast need to play it. seems your idea is good = prosperous but pussy and evil = badass and warlike.
not that simple also in DF there is no 'magic' (yeah i know we have dragons ect but there aint no spells or anything like that) so how do the crops increase in yield? another thing would be good = pussy is just awful, i would like to see absolutely no variance of power based on ethical alignment. also i feel a evil living deity would be selfish as fuck, even neutral would be ok with just legging it in the face of a full siege. they would probably march out to wipe out some raids to boots their followers faith and to home their own skills in combat but otherwise just sit there and make demands.
getting more into 'evil god = total prick' their behaviour towards their followers would be based on 3 things, it's own power, its followers power, it's followers faith.
-god is moderate in strength with a bunch of really strong followers with weak faith, it would try and bolster their belief before making huge demands. it's evil logic would say that they would be happy kicking it out/killing it if it was too much of a burden.
-god is strong and has really weak followers with weak faith, would slaughter some and turn the rest into fanatics through fear.
-god is really strong with really strong and faithful followers, would make them do nearly everything form fighting to sizeable but manageable demands. (not gonna risk loosing a good thing now is it?)
-god is really weak with strong to moderate followers, demands above all else sacrifices which either through eating or fighting them makes it stronger. has a risk of becoming too powerful and deciding to destroy the fortress now it has no more use for it.
-god is really strong with weak but faithful followers, fights for them but makes massive demands, happy to kill and punish for failure.
in the end good or neutral gods would be the only kind that would really bother going out to fight alongside it's worshippers.