Justin,
I haven't run the numbers, and it looks like you have, so take this for what it is worth (i.e. maybe nothing). IMO, (disregarding the variable portion of your withdrawal strategy) the fixed portion (starting at 40K and adjusting for inflation, regardless of the performance of your portfolio) puts you at risk of getting into a bad situation. You could find yourself in the situation youbet described--taking a big % of your portfolio's value because it hasn't kept up with inflation and/or the rate of your previous withdrawals. Are you realy going to take out 40K PLUS the variable portion if your portfolio has declines to $500K? If you think you will, then I think you may need to really reconsider this. If you can see that you'd never do that, then it would seem best to start with a plan that is more tightly pegged to your portfolio's changing value from the start (allowing you to make spending decisions more gradually, rather than getting into a hole). For me, that would be something close to ESRBob's "4%variable with a 95% floor" approach.
But:, re-read the first line above.
I haven't run the numbers, and it looks like you have, so take this for what it is worth (i.e. maybe nothing). IMO, (disregarding the variable portion of your withdrawal strategy) the fixed portion (starting at 40K and adjusting for inflation, regardless of the performance of your portfolio) puts you at risk of getting into a bad situation. You could find yourself in the situation youbet described--taking a big % of your portfolio's value because it hasn't kept up with inflation and/or the rate of your previous withdrawals. Are you realy going to take out 40K PLUS the variable portion if your portfolio has declines to $500K? If you think you will, then I think you may need to really reconsider this. If you can see that you'd never do that, then it would seem best to start with a plan that is more tightly pegged to your portfolio's changing value from the start (allowing you to make spending decisions more gradually, rather than getting into a hole). For me, that would be something close to ESRBob's "4%variable with a 95% floor" approach.
But:, re-read the first line above.