I like the idea, I personally would love to see the SMN class be versatile and able to switch roles. Want to play a tank, well summon a tank pet which will provoke and hold hate, want to be a DD, summon a DD mob, like above.

I think with several summons the summoner could fill several roles within a party. There will need to be balance, but SE can work out those details.

All in all, good thoughts, I'll be excited to get my hands on some new classes soon.