Is P.G. similar to a combination of the
Retiree Portfolio Model and
Case Study Spreadsheet tools?
In other words, how do the above tools compare with each other?
No comparison, Pralana is ridiculously more full featured than those. I won't do it justice, you can download the manual for free and there is a free "bronze" version that shows you the general look and feel, but the free stuff doesn't let you do anything fancy.
A few nuggets of what it can handle:
Cash is separate from your stocks and bonds, so for instance you can start with a stack of cash and spend that down. It handles HSAs, 529s, after tax basis in IRAs, inherited IRAs, Inherited Roths, life insurance, early mortgage payments, loans for college, charitable giving.
Allows income of lots of different types with different tax treatment, from wage income with SS taxes due and company match to 401k, to pensions, annuities reverse mortgages and any other continuing or one time taxable or non taxable thing you can dream up.
You can reinvest dividends or not, input a capital loss carryover, average unrealized capital gains. It will do cash flow including capital gains and taxes on them (puts CG taxes into the following year), ACA premium credits for one or both of you, SS taxation, IRMAA, NIIT, AMT. You input year by year Roth conversions limited by the most restrictive of your choice of tax bracket, IRMAA tier or FPL and it instantly tells you the impact.
There are lots of withdrawal strategies available like Consumption Smoothing, Actuarial, constant spending, % of portfolio, floor and ceiling, Guyton-Klinger, CAPE rules.
You set the priority of what order to draw from the four big types of accounts (taxable, your tax deferred, spouse tax deferred, Roth). You can make special withdrawal from any account at any time (for instance, I have stored up receipts to take a chunk out of my HSA, but will wait a few years).
It shows historical and Monte Carlo results as decile bands (rather than the spaghetti graphs in FireCalc). You can even select a start year and see how your plan would have fared.
You can do one-click studies on returns, longevity, inflation, SS claim age, stop work age, long term care need.
Not trying to be a commercial for it, I'm sure other paid programs are powerful too, but using freebie or home-brew programs when there are low-cost, super-powerful tools and there is a lot of money riding on the answer doesn't seem like a good bet to me.