With regards to using regen as a primary mana source i would advise against it.
Back in the day when people could get more than 100 regen if they geared for it, it was viable to change your playstyle to involve it, but now with people struggling to push 60 regen whilst gimping their other stats its just not worth it. Finding enough time whilst not casting to regen enough mana to make it worth while, and you will quite likely find yourself overhealing teammates inorder to stop them dying inbetween your regen bouts. Its far better to just take mp5 and int than spirit so you dont have to worry about this. Also as an O priest you will be casting dispell all over the shop and will be unable to prepare for regen bouts any would find yourself unable to do so.
That said if you can pick up regen on items easily then feel free to do so, just as long as it isnt at the expense of other stats. You should also have a 20spirit staff for those situations where you are able to regen though.
Back in the day when people could get more than 100 regen if they geared for it, it was viable to change your playstyle to involve it, but now with people struggling to push 60 regen whilst gimping their other stats its just not worth it. Finding enough time whilst not casting to regen enough mana to make it worth while, and you will quite likely find yourself overhealing teammates inorder to stop them dying inbetween your regen bouts. Its far better to just take mp5 and int than spirit so you dont have to worry about this. Also as an O priest you will be casting dispell all over the shop and will be unable to prepare for regen bouts any would find yourself unable to do so.
That said if you can pick up regen on items easily then feel free to do so, just as long as it isnt at the expense of other stats. You should also have a 20spirit staff for those situations where you are able to regen though.