Interesting Derail, I cant really add much to the list beyond raiding level toons usually have clickies for dispel, EB items, and so forth.
the most versatile, self-contained group would be Pal (rez/tank) / Enc (slow/mez/charm/voq) / Dru (heal/nuke/port/buff.)
Sounds good- Speaking from a 65 perspective, Paladin can provide stuns too to aid with chanter recharming his pet. The only thing you would be missing is Pet pulling to some extent, and FD, which is easily bypassed via Pacify in many cases (not all!) I want to say Enchanters get Pet Hold..??
The only real buffing weakness due to lack of shaman would be the lack of Focus/Sta (Sta on the Pal should be maxed or close to it anyways, Vallons provides some dex and agi (dru does str if by chance its not maxed)) And Avatar, I suppose, for the extra atk. I imagine not having a shaman hurts more in the debuffing department inasfar as charming.
Pal -Cleric buffing difference for AC/HP (assuming both use dru9) is a "mere" 210 hp and 17 AC at 65. Course, you'd never be able to use the Paladin's "focus-type but stacks with Focus" self-buff while using dru9.