So, given I've got a fair amount of AMS with 3 class structures (Ritual, Necromantic, PPF), any suggestions for fill-ins for the 4th class in each case?
Ritualist, Ritual Warrior, Martyr would need a skill monkey (roughly).
PPF could be Historian, Historian, Chrono, Echo, since the Historian can double or even triple up.
Overlord, Necromancer, Overlord is already a 4 person party, or even a 5 person, but should probably have one more just because. Skill monkey is decidedly missing.
And as a random side note, having Jack and Cokes with a 2L bottle of Jack makes one feel rather like a drunkard, even when only having one or two.
On that front, would we say... Warblade, Bard, Beguiler/Warmage? They're all roughly Tier 3 (Warmage is sometimes lower, depends on the build), and fairly well accepted as balanced medium classes. What I don't know is what the 4th (divine) class would be. CoDZilla is clearly Tier 1 and Spirit Shaman/Favoured Soul/Shugenja Tier 2, and then you have the Healer down at 5...
I don't think that covering each power source (martial/arcane/divine/etc) should be the goal for the control group, so much as party role. Beatstick/Meatshield, Crowd Control, Support/Buffer, Skill Monkey, and possibly a Generalist 5th wheel.
Warblade, Beguiler, Bard, and Factotum cover the first four roles well if you don't mind some minor overlap between Beguiler/Bard. If you want to include tier 4 classes, Barbarian, Warmage, Dragon Shaman and Rogue, fit the bill for each respective role.
Thinking on it, should there be more than one control group, if only for the sake of weeding out obstacles that are a bit oddball and end up easy for one group but difficult for another of the same tier? It might also be a good idea to test things twice, once with 'ideal' conditions (32 point buy, 2 flaws, all books) and once with non-ideal conditions (26 point buy, no flaws, limited books) to make sure the class doesn't experience an especially jarring jump or drop in effectiveness under different games (at least no more than normal).
I think the problem with running everything with 2-4 groups (Tier 3 vs Tier 4, 32pb vs 26pb) is just the amount of time required before we even get to running homebrew classes through the arena. Especially with 5 or 6 different attempts required per group.
My personal preference (which I always run my games with) is 32pb, no flaws, but like many homebrewers, I'm doing this at least partially because I think the WotC classes & material are usually broken in various ways.
The group suggestion works fine for me, I just don't know Factotum that well, so I'd need someone else to run that class, at least, through the arena. Although I'd prefer to stick with 4 people in the party, since it is what D&D always says it's aimed at.