Well, there's room to argue that a "+1 spellcasting level" bonus could also apply to Initiator level, or Manifestor level, or any other system variant, but that would be down to the GM and players to sort out on a local level.
My feeling is that when presenting a rules add-on you should only assume use and possession of the core rules, unless specifically aiming for an "Expanded Book of Nine Swords" or whatever. Plus, there's that whole Open Content thing....
Which is really to say not to expect anything specifically designed for Swordsages, or Binders, or Duskblades, etc. as I can't legally refer to 'em!
Addendum to that thought: Also, I personally dislike the ethos that crept in towards the end of 3.5E, that moved from options that, whilst they suited some classes better than others, were still more or less available to all, towards options that were specifically geared to one character class, or even one type of build of character class. Plus they explicitly told you in the books *how* to best build a character.
There's a column by Monte Cook where he outlines one of the design decisions in creating 3rd Ed. Sure, everyone eventually figures that taking Weapon Focus (longsword) is a good choice for a fighter, Toughness is almost a must for a Wizard, and that Magic Missile will see more use than Animate Rope, etc., but *discovering* that is the "hidden" game, and I think all those "how to build a Ruby Knight Vindicator" stuff that they added in for 3.5 kind of killed it.
Sorry, bit of a rant there! Not aimed at any of you!