Help Should I trade my secure job at a bank for a startup?

Ok, so I'm a Sr Developer at the bank where I have been working for two and a half years, and I'm getting really sick of the corporate culture and how long it takes to get anything done. My team is great, my manager is great, the product is alright, and I am paid alright considering that it's a conservative bank (and region). I just wish I were doing more hacking and less meetings/requirements proofreading/blah blah blah.

So I got a job offer from a local startup that has a product out there and some paying customers (although they aren't breaking even yet). This startup has made me an offer for only a little more then I am currently making, and the location change will add about 30 or 40 minutes to my daily commute.

On the plus side, I would be the second developer to join the team, so I'm getting in pretty early, and they have plans for a strong bonus program, once they break even (which probably won't be this year). I would have a lot of freedom, and a lot of input into the direction of the product and the development process.

My brother works for another smaller company who's founder is also one of the partners on this startup, and he has strongly suggested that I take the job. From what he's seen at his company (with a common founder) has been great and he really enjoys the culture and effectiveness of the organization. I am really excited about the opportunity but because it's not a very large salary jump (money being one of the main factors in my job search) I am having a difficult time convincing myself and my wife that this is a good move for us. We lose the known security and face the unknown.

I feel like I can get in there and help them get more of their product up to speed and get things really rocking that I could really see a possibility for some big returns, both monetarily and in my career, but it's scary to leave the security of a bank for a startup.

I've put together a list of pros and cons, but can you guys give me any additional insight, for or against?

Pros: Quarterly Bonuses (possible) Work from home more Startup culture and opportunities Ground floor, one of the first employees Launching board for my own ideas

Cons Only a little more money then I am making now Small/unstable What if they don't pan out? 30 to 40 more minutes to the daily commute

Thoughts? Other pros/cons?

Thanks!