My advice is to max out your 401K contributions every year, especially at your age. The contributions are not taxed, thereby providing an instant return and more capital to earn investment income from. The contributions will also grow tax-free until they are withdrawn. The contributions are periodic by nature and therefore provide the benefit of dollar cost averaging.

I would caution you to think carefully about how much weight to place on outright guesses as to what the government may or may not due regarding future tax rates. Forecasting what the government will have in place in this regard 30 or 40 years from now may be a fool’s errand.

My own 401K is heavily weighted toward an S&P 500 index fund (40%), which you have as an option in your fund selections. I would encourage exposure to small cap stocks as well.

I’m a big advocate of 401K’s. I started investing early but didn’t max out, and really wish I had. I may be wrong but I would doubt that you will look back in 10, 20, 30 years and say “damn, I wish I contributed less money to my 401K”. But, to each his own.