Another point about the bard: The way the class is written, bards can use the Manual of Puissance at Arms and the Manual of Stealthy Pilfering. These magic items grant, respectively, an additional level of fighter (Puissance) or thief (Pilfering). I had a bard character years ago who went to max level fighter, then to max level thief, then switched to bard, managed to acquire each of these, and used them.
Also, according to the PHB: "A bard must have scores of 15 or better in the following abilities: strength, wisdom, dexterity and charisma. Furthermore, a bard must have at least a 12 score in intelligence and a 10 in constitution." This is in direct contradiction to "the character with two classes", which states "In order to switch from one class to another, the character must have an ability score of 15 or more in the principal attribute(s) ability of the original class and a 17 or 18 in the principal attribute(s) of the class changed to."
A bard only has to have a 15 in dexterity, not a 17, which would be a prerequisite for changing to thief. The way it was implemented in pencil and paper in the game I played the bard in was that, if dexterity was 15-16 (my bard's dex was 15, I think), one did not actually change to "thief", one changed to "bard-in-training", which was 100% identitical to "thief", with all the limits of "character with two classes" but a hard level cap of 9th level for "thief" abilities (excepting the use of a Wish/Limited Wish/Manual of Stealthy Pilfering AFTER becoming a fully-fledged bard).