I want to try help Bodhi instead of Aran (already tried)...is this harder or are there any other advantages or disadvantages on helping her?

They both end up in the same place.
I went the same path as you and am not having any problems but some people have said that you should only go this way if you do not have a good alignment party.
The only point when this effected me was when I was given a choice to do a good alignment or evil alignment quest.
In other words it doesn't matter really.

spoiler.
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well one way you end up fighting undead, one way you end up fighting pretty powerful theif/mages

I am going to help bodhi this time, kick arans ass.

Then i'll also kick aran's ass this time!

Spoiler to anyone who hasn't got to chap 4:


I was thinking about the whole good and evil thing, and to be honest, it doesn't seem either of them are really good quests. I mean, the vamp one is more evil, but you are helping the shadow thieves here. Also, while it is an evil quest, would an evil person choose that quest even though you come out looking like an idiot for falling right into Bhodi and Irenicus' hands. I don't think so. My evil fighter priest of talos is smarter than that. I'll use these weakling thieves to my advantage in my quest to tap my evil powers and rule the world. HAHA HAHA HA!!!!!!!!