Should I switch to Roth contributions in my 401(k)?

A lot of ink has been used across the Internet on this, so let's just cut to the core issue here. Roth contributions are great if you're in a higher tax bracket in the future than you are now. Traditional contributions are great in the opposite situation (your future tax bracket is lower than your tax bracket today). Since no one can predict the future direction of the US tax system, having a bit of both is the optimal hedge-your-bets strategy.

That said, most people get their Roth exposure through their IRA, and Traditional through their 401(k). But, if you don't have a Roth IRA, or your Roth IRA is much smaller than your 401(k) account, then making some Roth contributions to your 401(k) makes sense to balance out the tax risk.

There's a bunch more arcane details that you can usually safely ignore (your employer matching always goes into your 401(k) "Traditional" because a Roth 401(k) is really just a Roth Provision on a Traditional 401(k), etc) but the simple idea above is the core picture.