Actually, I think that a maneuver progression based on the core class is a better alternative than the standard approach for Tome of Battle classes; it would stiull acknowledge the difference in the readying progress and the different learning speed which is, for example, the one advantage of the Swordsage. This is insofar relevant since - as far as I know - the characters keep their readying mechanisms.
In the case of the Mercury Duelist, for example, a warblade-oriented maneuver progression would be no issue for a warblade, but would cut down a swordsage's progression by half, vice versa, it would doulbe a warblade's progression when it follows a more swordsage-oriented model, and with a class that well might be interesting for both classes (Diamond Mind is on both's discipline's lists), this way is just a bit fairer, as it comes closer to treat each class according to its strengths and quirks.