One thing to take into consideration -- and I've seen this become an issue on several occasions -- is that there is a lot more work required of the technical co-founder. There's a point at which all of non-technical 'work-long-hours-to-produce-a-deliverable-under-deadline' work is done and then the effort switches over to making the occasional document/presentation revision and taking meetings, etc. This tends to happen way before the product is shipped. It's at that point that the techie catches the non-techie browsing boing boing or watching youtube videos and s/he starts to feel resentment.
That's when the stock split can sometimes start to seem inequitable in the eyes of the techie unless the split is heavily slanted in favor of the techie, simply because it's natural to think of 'value add' in terms of 'time invested' and not some other difficult-to-measure metric.
I know that doesn't answer your question, but no matter what you choose, it's a good idea for both people to discuss and understand the value of their contributions in terms other than the number of hours spent in front of the computer.