I do have an IRA through Betterment that I have at a more aggressive setting that is at 90/10 stocks/bonds. It's a small amount (under 10K) that I just let Betterment manage.
I have never thought about using that as my bond allocation. I have read elsewhere that perhaps I should just consider my anticipated pension as my bonds and go 100% stocks.
With the recent drops, this might be a good time to switch over since prices are lower now.
Going 100% stock is a viable option, depending mostly on how squeamish you are about volatility. If you're going to hold bonds I would consider doing it in your IRA where you can get a much lower expense ratio than 0.45%.
Regardless of what you do with your asset allocation I tend to agree with
@degrom7 -- leave betterment for Vanguard, Fidelity, or Schwab and pick a low cost index fund that fits with your desired asset allocation.