Well, in any case I think wizards, clerics, and druids, even using just core rules only for them, can still outperform Bo9S characters and kick their butts. The martial adepts just get the advantage of being tougher without needing spells to do so, and can do their tricks in more battles per day, but can only use each trick just once per battle (or once per few rounds if they waste a round just recovering maneuvers).
Spellcasters can use the same powerful attacks for multiple rounds in a row, but can't keep it up all day long, while a martial adept can only use strong attacks once every few rounds at best if they waste some time (or once per battle if they can't afford to waste any time in the heat of battle, which will probably only come up once in a while), but can do it in every single battle of the day.
I'll make a high-level example first, then I'll see if I can make a similarly effective lower-level combo later.
[sblock=example]Halfling transmuter wizard 17, Dex 30 (base 18, +2 racial, +6 gloves, +4 inherant from a manual), Int 30 (base 18, +6 circlet, +4 from levels, +2 inherant from a tome); possible with 32 point buy, more likely with a higher point buy or just good rolls
Feats: Scribe Scroll, Improved Initiative, Spell Focus (Enchantment), Greater Spell Focus (Enchantment), Spell Focus (Conjuration), Augment Summoning, Spell Penetration, Heighten Spell, Quicken Spell, Craft Rod
Relevant Possessions: Greater Metamagic Rod of Quicken Spell, Normal Metamagic Rod of Quicken Spell, Gloves of Dexterity +6, Circlet of Intelligence +6
Spell Slots: 4+1/7+1/7+1/6+1/6+1/6+1/6+1/4+1/3+1/2+1
Halfling transmuter and random 17th-level martial adept encounter each other on the road, recognizing one another as mortal enemies for whatever reason. Halfling wins initiative easily; the martial adept has had to split his/her best ability score rolls and bonuses amongst at least three scores while putting at least decent boosts into one or two other scores, and is unlikely to have anything comparable in Dexterity, especially given their minimal ranged attack capabilities.
The halfling opens up with a Quickened Hold Person, using the Normal Metamagic Rod, and Heightened to 6th-level, for a total Will save DC of 28. Martial adept is flat-footed since they lost Initiative, and can't use Moment of Perfect Mind in that state. Martial adept probably fails the Will save, unless they're a Swordsage, in which case they have a decent chance of success. Halfling follows up with a Time Stop, rolling average for 3 rounds of effective free time.
1st round of Time Stop, the halfling uses a Quickened Teleport on himself, using the Normal Metamagic Rod, to arrive somewhere mostly concealed and behind the martial adept. Then he casts Summon Monster VIII to get critters from the SM6 list, with an average result of 3. He summons 3 Gargantuan Fiendish Monstrous Centipedes, surrounding the martial adept with 2 of them flanking.
2nd round of Time Stop, the halfling uses a Quickened Invisibility on himself, using a 6th-level slot. Then he casts SM8 again but for only 1 creature, a Gargantuan Fiendish Monstrous Spider, to flank with the 3rd Centipede.
3rd round of Time Stop, the halfling casts a Summon Monster VI, quickened by the Normal Metamagic Rod, to summon a Janni flying above the martial adept. At this point the only direction the martial adept isn't surrounded is underneath; the gargantuan flankers are plenty tall enough to block him leaving any other way except straight up, where the Janni is hovering to block him.
Time Stop ends. The halfling calls out a command to have his minions deliver a coup de grace and smiting. Martial adept suffers 5 automatic critical hits as the summoned critters act immediately after their summoner's initiative, executing a coup de grace upon the martial adept that is currently under Hold Person.
Each except for the Janni will most likely, given their average damage with their Smite Good (assuming the martial adept is good-aligned; if a different alignment then the halfling has to summon different stuff for the same degree of effectiveness; if he doesn't know he can just hope that the damage is enough without successful Smites), will provoke not only a Fortitude save against the coup de grace attempt, but also additional Fortitude saves against massive damage.
Most likely one of those DC 20-50-something saves (20-odd for the Janni, 50-60-odd for the bigger summons) is going to fail and you wind up with 1 very dead martial adept. And the halfling can repeat this one or two more times per day at least, though using up his metamagic rods after the second time, resorting to some slightly-lower-level Summons after the first barrage and no Quickened Fly/Teleport/Invisibility-type stuff.
Even if the martial adept survives by some miracle, he's going to have difficulty getting out of that jam, and if even just one of those gargantuan critters survives the round, it will be commanded to grapple him next and thereby neutralize most of his best attacks, while the halfling makes attempts to Disintegrate him, Scorching Ray and Quickened Scorching Ray him (the halfling has great chances of hitting with the ranged touch attacks), or summon more Huge or Gargantuan beasties to grapple and maul the martial adept. And that's assuming the Hold Person didn't stick. In which case he'll probably start off by attempting another Quickened Hold Person followed by a normal Hold Person if necessary, until the martial adept has expended its few emergency-butt-saving maneuvers.
Even if the halfling loses Initiative from very poor rolling, his likely Contingency will transport him a safe distance away before he comes to any harm, so he can ready a separate (probably invisible, and probably including an initial Dispel or Greater Dispel on the martial adept, to suppress any True Seeing items or the like) ambush.[/sblock]
