LostSoul
Adventurer
I think the terminology narms me, too. "I have journeyman perception" is meaningless jargon to me (and to any newbies, I imagine), but "When I swim, I roll this dice and get this bonus, and if I get high, I do it well" is pretty intuitive.
"Journeyman":
1. One who has fully served an apprenticeship in a trade or craft and is a qualified worker in another's employ.
2. An experienced and competent but undistinguished worker.
DC 15:
??
In order to make sense of "DC 15", I'd have to perform a mechanical analysis of the system. Saying "Journeyman" actually means something that's easily accessible, whereas calculating what "DC 15" means in the context of the game is not. (Which is where 4E's DCs by skill level tables come in handy.)
Auto-Success and Auto-Failure actively work against that, since what you have is what you have. The result -- barring heavy DM intervention -- is said and done with. Now, that's often a useful outcome -- I don't necessarily want to have to make the barbarian roll to move a statue around. But that's what passive skill checks ("Take 10" and the like) are for. They don't fail at providing auto-success, what they do fail at is providing auto-failure.
So auto-failure isn't an appealing selling point to me. I don't need to be more empowered to say no.
It's only auto-failure if the players can't think of anything to do that will improve their ability to succeed.
Now, when you say "barring heavy DM intervention":
I am a lazy DM. I do not want to have to make thousands of micro-judgments about the permissiveness and results of an action that the rules don't handle. Furthermore, I like players to be empowered to change the world on their own, rather than asking me for permission at each turn. The more active they are, the more reactive I can be, and the easier my job is.
So I guess the two things I see this system potentially accomplishing that the current skill system can't already accomplish are both things that would reduce the fun of the game for me. I don't want to adjudicate permissible actions, and I don't desire stronger rules authority to say "No."
If you don't want to make judgement calls, this is going to be a bad system. However, this system - if the challenges are auto-failures - is going to engage players who want their characters to succeed. They are going to have to empower themselves to make decisions for their characters that turn auto-failures into auto-successes. You're given authority to judge the player's decisions for their PCs. If this responsibility is something you don't want, the skill system isn't going to work.
In a similar fashion, if the players are the type who fear failure and won't engage because the game challenges their skill, this won't work for them. But if they are willing to "step on up" to the challenge - it's going to empower them and bring them into the game.