The fallacy that I see with the calculator, is that it assumes a constant even growth rate of your assets (You just plug in a number of what percentage they are growing). One of the uncontrollable factors of the withdrawal stage is the sequence of investment returns. In the first 10 years of retirement, a severe market downturn would greatly increase a portfolio's chance of failure. Paying more taxes by moving money from a Regular IRA to a ROTH IRA exacerbates this even further.
ORP does have a Monte Carlo feature.
No tool of this nature is perfect. The ones that are available all seem to have their strengths and weaknesses. They all require the user to make some assumptions, such as length of plan, inflation rate, social security benefit (as there seems to be some uncertainty that we will receive what current SS estimates say we will), do you plan to work in retirement and how much will you make and for how long, etc. The deterministic ones require you to specify returns...
The future is uncertain. You just have to plan for yourself using the assumptions that you think are most likely to materialize, or if you prefer, use worst case assumptions. Either way, you are probably going to be off. If someone strongly believes the first n years of his retirement will see overwhelmingly negative returns, that person might be better off in CD's.
My take away from this; If you are in a stable or Up market environment, paying some more in taxes to reduce future tax liability may be good thing. Not so much in a severe market downturn.
Roger that.
I think you are trying to put too fine a point on this. Use these tools to establish a general direction, not a precise compass heading. If you don't like what one tool is telling you, then that probably is not the tool for you.
Personally, I use Fidelity RIP, ORP, FireCalc, and Quicken Retirement Planner AKA Lifetime Planner. I generally use 90% of assets, 3% inflation, and 2.5% real return, and do runs with 100% of SS benefits and 75% SS benefits. FireCalc gets four runs, two in deterministic mode, and two in its native mode. My approach is probably opposite from what most people do. I have the tool solve for the amount I can safely spend per year, then decide if my budget can live with that amount. FireCalc and ORP do this effortlessly. With RIP and Quicken I do this by varying the annual expenses until the plan breaks, then back off the expense number a little. Sounds difficult but it takes just a few runs if you use a binary search to home in on the expense number. Summarize this into a little 5x2 spreadsheet and analyze by closing one eye, and squinting with the other eye until the numbers are fuzzy but readable, and usually conclude everything will be OK.
You might consider sending an email to James S Welch Jr.
orplanner@gmail.com <orplanner@gmail.com