i know that most theurgs went for a high seren Ra spec but with the recient serenity "fix" what choice Ra's should one choose pre RR5???

I would spec like this
4L2 = Moc2 Purge1 Mcl1 Raging Power 1 Physical defence 1
4L4 = Moc2 Purge1 Mcl1 Raging Power 1 Physical defence 2
5L0 = Moc2 Purge1 Mcl1 Raging Power 1 Physical defence 3
5L4 = Moc2 Purge1 Mcl1 Raging Power 1 Physical defence 3 Dex2
6L4 = Moc2 Purge1 Mcl1 Raging Power 2 Physical defence 3 Dex2

you can also go for Raging power 2 first, so 6L0 RP2 and 6L4 dex2 than, as you prefer.

with 6l + you should know best what kind of grps you run etc. and what you need next.

also concentration is kinda useless now, since a quickcast costs you x2 mana, so i prefer Moc2+, just make sure u mainly use earth pets, they still gonna last 30 sec with Moc2