IanB said:against medium creatures. Unless you're talking about an incredibly narrow scope of events, how *often* something is broken is not terribly relevant to the question of whether it should be allowed in a game. Anything that is broken as often as "any time you are fighting medium or smaller creatures" needs to be fixed, period.
Hmm...while I'm of the "SDS isn't inherently broken" camp, I don't think arguing "any time you are fighting medium or smaller creature" is a valid argument since using the monster filter, from CR 13 go up, you shouldn't be fighting medium or smaller creatures since assuming you are a good party (a fair assumption), the only non-good creature from the SRD that is of that size or smaller are the Werewolf and the Mummy Lords (and the mummy itself is already immune to SDS so you really only have the Werewolf Lord as a medium sized creature.
Sure, the mooks and the minions have a good chance to be smaller but then, a regular full attack should kill them OUTRIGHT.
re: Stun Effects in Manoeuvers
Strange, I tend to find stun effects manoeuvers less problematic than pure damage. Rystil, I think you mentioned you allow the FB and yet have more problems with the STUN effect of some manoeuvers? For our campaigns, stunning is easily dealt with as listed in manoeuvers since a number of creatures (constructs, elementals, oozes, plants and undeads) are plain immune to it and unlike say the illithid mind blast, it only lasts 1 round meaning it best works in a party environment which, again, I'm more likely to allow.
(Plain and simple, if ability X gets more powerful with more party members while ability Y is static but in the individual case, is more powerful than X, I will look more harshly on ability Y)
There's just not much one can do to mitigate the damage dished out by a FB. Worse yet, howabout a barbarian with the class subsitution from Complete Divine that gives the Pounce ability who then takes FB.
re: Warmaster's Charge
The reason why I think this should be uncapped is that I WANT players to try and break it since, unlike say Shapechange, the player can't simply metagame to make it broken. This manoeuver only gets broken with the player IN_GAME using above average teamwork, setting up favourable environmental conditions (something which is pretty much dependent on the DM being lenient) and a fair bit of luck (the target has so many options and low-level at that since even a windwall plays havoc) to get massive damage. This manoeuver, if you actually get it to work, is the time of thing you talk about for years afterward. For a 17th level melee combatant, I WANT this to work.
Now remember, this is a 9th level manoeuver thus at least a 17th level party where the usual shenanigans is simply "I use spell X, I win". That's it and frankly, not very memorable IMHO.