i have to say that last boss in PoS will be tough for undergeared group, boss has 1 mil hp, and his mount has 500k(you have to burn through about 50% of that to access the boss) quite a bit of damage going around too.
The first 5 man is about same difficulty as ToC, but only 2 bosses.

When i cleared them both, only my tank had some toc gear, Ive got a lot more gear on my team since then :P

I'll try to go back and make some videos next mon or tue when work slows down.