Is this a good campaign idea?

[xykonthelich]

So in this new campaign setting that I am making, I cam up with this idea that I think is really good. Im just not sure if I am making some huge mistake.

So I have this huge world that I am creating for the setting and so that is theoretically covered. The main concept about it that I think is really cool is: the PCs all start out as level 1 Commoners in a small peaceful village. The way that they progress in levels of classes besides Commoner is by gaining xp in the zone of expertise that the new class contains(example: a PC wants to become an assassin so they seek out an assassin's guild or an individual assassin and find some way to recieve training from them.)(example: a PC wishes to be a bard so they attempt to join a travelling group of troubadors for a time and gain xp under them.). So any levels that are gained by the character while under a sort of training would go to that class. If the character is not gaining xp in any specific class's area, then any levels that they gain are levels of Commoner. That may seem very restricting but I am working on a way to enable the PCs to turn their Commoner levels into some other class
(not without earning it of course).

I think that the original hook to pull the PCs out of their village is some completely unexpected goblin raid that wipes out the village and forces them to seek shelter elsewhere. This raid could also lead to the first adventure of the campaign.

Well thats not even the half of it but I would appreciate imput from all you experts. This is my first campaign setting as you can probably figure out. So yeah, feel free to make suggestions and asks questions.

Edit: obviously they all start out together as they live in the same village, but I am in the process of developing a system that allows them to split up and fit each of their "scenes" into a single session. Any further suggestions about creating that system would be welcome. Also, I have already discussed this idea with my players and they all think that it would work very well, even if they were split up, if we had a good system for working that out. I also know that some of them would still stick together for segments of the campaign(as in team up for some adventures and cooperate for a while) which would make that a little easier.

[Omeganaut]

That sounds like it could be a very good idea that encourages the players to really invest in their chosen paths rather than just try and get xp. Be careful that characters can still pick up class levels by doing things the way their class would, not just by training. Pratical experience is as good as theoretical knowledge. As long as your players are fine with the system (Not just your idea, but the system you have to put it into play), then that should be fine. Just remember that a gimmick isn't everything, don't lose track of the plot because you are thinking about making sure your characters can advance down their chosen paths.

[Thrawn4]

I like it. It adds a lot of flavor. And I don't think it is necessary do re-train their first level of commoner, as it makes for a more realistic setting.
How will you manage the different tiers? Will it be more difficult to get access to the mage's guild than to the bards? I would imagine that one would have to solve some side-quests for the mages, while for the bards you only have to solve a riddle or learn a special trick.

[Yora]

The problem is, that the characters would have to do different things to advance, but at the same time you want them to work together as a group.
Constantly going on adventure that only benefit one player in the group will likely not be much fun for anyone who isn't having his turn.