I sort of did a Herald of the Titans team thing for a while. Every raid instance as far as I could at level.

The distribution of spells for some classes is pretty harsh, so many 'raid' spells are awarded at 72, 76 (Wild Growth!), etc that things are pretty tough class to class. Heirlooms seem to have that dip in scaling at the upgrading scaling. I couldn't find any tier bonuses that were mechanically worth it, all the TBC bonuses are broken, the spells don't exist, or the spell rotation wasnt boxing friendly.

That said the talents and the lack of spell ranks seems to be pretty huge in comparison to original content. Pets are also massively powered (at least warlocks that is).

The mechanics are still unnerfed, so while we have lost the ability to spam dispel/decurse ... the need to spam dispel exists still. I forget what spell i was always hunting for that was a go to spell for BWL, but wasn't available for me in BWL. Absorb and Atonement are huge, Void Walkers, Monks, and DK's are overpowered.

I was able to easily 10man heirloom at level MC & BWL, but AQ was horrible mostly with being chain feared poisoned and out ranged. Unless I got lucky in a corner area.

Of course I also don't have 40 characters to fill a whole raid, so yes it would a face roll with a whole raid.

I think it helped me greatly boxing in the end.

I would be all over it for single healing or >=85 content.