I debated answering this post, because I'm fairly sure you're not going to listen to me, but I need to do some warm-up writing, so here we goes.
Don't do this. I'm pretty sure I know you, because I was you in 1999. Let me make a few guesses (and I haven't looked at your forum profile):
You're in your mid-20s. You live in San Francisco or the Peninsula, South Bay. You work for a startup that has been dubbed a unicorn by the pliant tech press. You have a bunch of options, and you're trying to figure out the tax advantages of buying now, holding for a year, assuming an increase, and then selling after. Instead of paying 39% on those, you'll pay gains and save 20% or whatever.
A few Yes/No questions that you should ask yourself:
Do you work for Uber or Airbnb?
Do you work for Pinterest?
If either of those was "yes," then stop right now. Most of the value that those companies will generate has already been factored in, and any IPO won't gain anything. If you work for Pinterest, those options aren't going to be worth all that much. Then read on.
Does the company you work for make money by selling things for more money that it costs them to create and market them?
I am fairly sure your answer here will be "no." You're at a startup and they're growing and burning cash. What this means is that you've got about a 10% chance of this particular unicorn returning value over and above the private financing. A bunch of these companies will fail. Others will be absorbed at a loss into other, larger organizations. It's going to be rough, but it's definitely happening within your five-year window. So, given that:
Can you accept a 90% chance that you'll be paying back that loan with your salary?
I got a solicitation for a $100k personal loan the other day. Interest rate was 10%. That's a monthly payment of around two grand. Given that your company has a 90% chance of failure, which will mean that you won't have a job, you're now putting yourself in a situation where you have $100k in savings (well, really, probably about $80k if you bring in penalties for cashing out a 401k early to pay your rent), $100k in debt, and a bunch of worthless stock.
Again, I'm not sure that you'll listen to me - everyone has to learn their own lessons, after all. But here's a good, solid life lesson:
Don't take out loans in order to gamble. Back during the last tech boom, I lost half of what I had because I was putting everything into overvalued dotcoms (and those were already public - I was able to sell at a loss instead of losing everything). A friend of mine did the same, but margin-traded. I learned a lesson, he got a bankruptcy. Don't do it.
In your position - 200k in income, plenty of it disposable - I'd probably throw more into those stock options, too. But do it with your own money.