We hope to retire at 50 and the 457 will serve a critical role in setting up a well-played Roth pipeline. I am tempted to move closer to 90/10 for this account to give it a chance to grow more, since if the market fails we could just not retire early. But, then I think it would be smarter to keep it conservative, since we will be accessing it first and we have less time to recover from corrections.
I am leaning towards 80/20 and moving towards a more conservative AA when we are within five years of accessing the account, but what are the different considerations for a tax-advantaged account you plan to draw from during early retirement?
There are two considerations, to my mind: taxes, and a minimum "floor" of safe investments.
1 - You're going to pay the taxes no matter what - so I'd recommend that you save in a brokerage, after-tax account and pay the taxes NOW, before the tax rates re-assert themselves to the 2016 brackets in 2026. It's not taxes that are the problem - it's the PENALTY for early withdrawals.
The other option is to save in a Roth account, where the withdrawal of contributions is always allowed. Note that if you draw down from this account prior to age 59.5, Roths also have penalties.
We have addressed this by having a 5 year plan of converting DH's SEP-IRA to a Roth. We offset the converted funds by shoveling an equal amount into my 457 account, which is accessible penalty-free after age 55. So he "pays the tax" on the converted dollars, and I "shelter the funds" by putting them into the 457, for a tax net-neutral maneuver. He'll be 59.5 next year, so we're almost there!
2 - The "floor" is what we've done for peace of mind. Our plan is a 3.5% withdrawal from our funds from age 60-65, 3.75% SWR at ages 66-70, and 4% after age 70. So that means I know approximately how much we need to have in TIPS, Cash, and bonds.
For example: if I know that the stock market typically takes 5 years to rebound from a bear market, I need 5 years x 4% (our highest planned withdrawal rate) - which magically means 20% of the portfolio.
So yes - we're 80/20 in our investment portfolio. I also have a pension, so this feels pretty reasonable to us.
You might want to read up on Liability Matching Portfolio (LMP) theory - it's a bit more sophisticated and complicated in its original form, but looking at your MINIMUM need, and stashing that in TIPS, cash and bonds is the crux of it. I just don't feel the need to do that for a 30 year time horizon, since we'll have a pension and 2 SocSec incomes, in addition to the portfolio.