While waiting for the update to launch, I thought we might revisit some older friends... with fewer numbers. My current challenges are:
Saru-surma T2C duo
Lost Temple T2C duo
Watcher 3-man
Reward for the first group to accomplish each is your choice of 50g, 50 T4 relics, or 3 SoGEs. Will take as evidence screenshots of bosses near defeat and after defeat. (Note that for SS and LT, you will need to take the same group through the entire instance without leaving it. Otherwise you lose HM.)
Will add OD to the list as soon as I figure out what's suitably hard in there.
Watcher with 4 is quite trivial. (Our group was warden/hunter/rk/mini, hardly the ideal class makeup.) Lost Temple HM we did with captain/champ/mini. SS would be as easy. I'd imagine captain/burg/rk or something of that sort. [-Edit: Did SS HM with guard/hunter/rk. Probably among the easier class combinations.]
But well, take one person out, and we might find the difficulty level increasing tremendously.
Pretty sure the watcher hits medium armor for more than 100 apiece. Anyhow, the reason why things like Watcher/LT/SS are challenges is not in the healing. It's more in figuring out the class roles (multiple roles). For example, each of the three bosses in SS may be duoed. But with the same two classes? That is the interesting part.
Besides, soloing things on-level (at 65) was quite limited by class. Dungeons? Wardens. Sword Halls (EM)? Guards, wardens, champs. Stoneheight T2? Wardens. T1, guards and champs. NCF spider/thadur? Captains and wardens (presumably guards). See a pattern? SG was duoed on level to Urchir (warden/rk). I have not done it with fewer than 4.
Foundry might be doable with 3, as it doesn't have a dps race component.
That said, all the "x class solo lists" have included below-level mobs and instances.