-Pay is most likely $70K. -Job is in SF. -I don't get school credit for this. -Will push my graduation date back either a semester or two semesters depending on how many credits I want to do per semester. -College Fund (Will graduate with no debt)
The reality is your going to get a year of experience but I don't think that is going to do a lot for your resume, and your putting off graduating a year.
As for getting the experience, well theres a ton of need in the open source world. If I were looking at two resumes where they were fresh out of school I'm going to look longer at your github account than the year you do at this job.
Based on the economics, I'd assess based on the a) the quality of the work you'd be doing and b) the quality of the startup.
To take two extremes, if you're working on creating CSS templates for a Django website, stay in school. If you're working on a deep learning model for speech recognition, this becomes interesting.
Same with the startup. Is it a startup with a bunch of customers already, or is it just an idea? Are the investors good? Are the founders people who seem like they can create a successful business? etc.
Financially speaking, if its the next facebook, then you'll be retired on an island somewhere. In almost all other scenarios, you'll end up worse off because you will be able to demand a higher salary post-graduation.
In terms of skills garnered, it probably will accelerate your technical skills, but you will miss out on the opportunity to solidify your network at school (which takes time) and to graduate with your class. Not to mention, depending on the quality of the startup, it might actually hurt your technical acumen if you are learning the wrong patterns.
I think a bigger question is... why now? What makes the draw to startups so strong that you want to leave school to do it? If the draw is to join a risky, hot-shot, fly-by-the-seat-of-your-pants company (as it was for me), then you might be in for a reality check when you're debugging spaghetti code for 8 hours a day. If you're really into the startup life, my advice would be to build a business while you have college as a safety net, then drop out once you have ramen profitability. The learning curve and potential payout there is way better than the opportunity to work at a crumby startup as an employee.
... and BTW, 70k in SF is a notch above starving. More than 50% of your take home would be going to rent at that salary, even if you're living with 6 roommates in the 'loin. With demand for devs through the roof, I'd demand 100k at least.