PostgreSQL Authentication and Pooling in JBoss : static 'postgres' user VS dynamic jboss user

Hello, and merry xmas,
Traditionally we have been using jboss JCA pools with postgresql by having every connection authenticate
against the static postgres user, or 3 other predifined static users.
This was working ok, but made debugging hard, there was no way to confidently link log from the jboss log
with log from postgresql, or just find out which user causes a faulty situation. The pgsql user was also one of those
4.
Lately i have been thinking of authenticating the connections in jboss JCA pools against the active web user,
i configured it, and it actually works in some tests i made. I find this more attractive, since it will give much
betterstatistics, 
( i would trust pgsql stats over jboss stats).
What i'd like to ask, is if anyone of you has done this and had a good experience. The resaons why i ask, is that
documentation in jboss is minimal regarding this issue, and the commonly usual practice is to use the same
user when creating connections in the pool. I should ask the jboss ppl as well, but my experiences on their camp
were not very encouraging (i never got any serious feedback from there).

Well, i'd just like to hear your thoughts on that.

--
Achilleas Mantzios