I'd prefer if "established tough adventurer" is somewhere around 5th level, so 1 level in any given class is kinda dinky. And then I'd start most of my games at 5th level.
Sure. 5th sounds reasonable.
So you want everyone to multiclass because it is overpowered?
Oh! Gods no! I'm not saying everyone
should multiclass...only that they
could if that's the kind of character they want. Single classed characters, especially with whatever little tidbits background and theme are going to add to your concept, are definitely what I would prefer to see in my games. The multiclassed/trained individual would/should be a unique or at least uncommon phenomenon.
I would also, expand on the original idea to perhaps include that you can only multiclass with one of them being the base-4 classes.
Fighter/Rogue = OK.
Fighter/Assassin = OK (a bit redundant, maybe, but OK).
Paladin/Assassin = NOT ok.
Fighter/Mage = OK.
Mage/Ranger = OK.
Ranger/Necromancer = NOT ok.
And then, when you're high enough to tack another class on, you're done multiclassing. 3 tops. No more 5 or 6 different levels of all kinds of things.
A few prestige classes or "trees" to specialize oneself with what they have...A Fighter/Rogue...who then wants to add some Assassin in the mix, fine. Then your DM can whip up a "Shadowswords Assassin Guildsman" to give you a few extra bells and whistles or some such.
The Ranger/Mage...tacks on some Illusionist and becomes an "Arcane Archer of the Unseen" or some such.
But that's all getting into the implementation of the idea...and the point of the thread is really just the idea in/of itself.
--SD