Generally, it sounds like a great opportunity, with lots of good work....
... I'm confident I would enjoy working with these other people more, as I've worked with them in the past. My only reservation (and it's a big one) is leaving my current firm after only 6 months full time. Is that a good reason to pass on this opportunity?
Couple points:
1. Don't underestimate the value of working with folks that you like. It can make a tough job much more tolerable.
2. Don't overestimate the value of a salary bump, especially if a lower paying job will ultimately give you better experience, or allow you to work with a more successful/experienced attorney. You are new to this business. Getting the best experience should be your goal. Once you have that experience (and the skills to go with it), you can become your own source of income.
3. Stability in an importwant consideration. Is the potentail new firm an established place of business (i.e., did your former colleagues merge into another existing firm)? Or is it a new shop? If the latter, what does their client base look like? Will they have enough work for the forseeable future to keep you employed? How about the existing job?
4. The value of staying a a firm for a year is somewhat overblown, particularly in the circumstances you describe. You have a very clear and understandable explanation for taking off for the new firm. So if that is the only thing stopping you from taking the new position, you might want to give serious thought as to whether you are overemphasizing the importance of the "1 year residence." No one will care whether you jumped ship to join a new firm 6 months after you started your first job. Particularly if you spend many years at the new firm.
5. Finally, It is alwasy best to take a measured approach to these situations. Due your due diligence, and find out as much as you can about the new firm and the old firm so that you can make an informed decision. You like working with your former colleagues, but what about other folks at the new firm? Are you prepared to deal with the lack of (or simply different) structure at the new firm? What are your prospects for upward mobility? Etc. These questions and more should be asked and answered before making a move one way or another. Otherwise you might find yourself facing one or more unpleasant surprises.
Good luck.
Klav