So tested bear again and he is still very strong when Buffed.
This is with full buffs CL50, spell res, energy immunity, death ward mindblanks knockdown etc etc.
Underdark castle EX1 basically i just followed him, a few casts of regen needed.
Dark lair non EX he takes quite a beating but still just keeps on ticking, whereas Golem died.
The druid spell lists potentially add +22AB + greater heroism. 116AB full. cleric and ranger bears will not get that , depending on if Greater Magic weapon works on animals after changes.
Checking spell lists rangers do get Greater magic fang and Natures Favour albeit at Half caster lvl, so for full pet buffs that at least 26 Ranger with practised caster, your pet is suitably weaker though then anyway.
Not sure what to suggest without gimping the other classes pets!
Awaken and enrage animal need attention as they allow multiple castings.
In theory the bear lvl in question would be what my character could have at the cost of one feat - natural bond. It just feels too strong