Before retiring I used i-orp, fidelity RIP, quicken lifetime planner, and went to get my plan better by my Schwab consultant (person assigned to me because I have a lot of money at Schwab. Schwab ran my plan through their modeling.
Truthfully, I learn more here than any FA adviser could tell me. A tax CPA might improve things a bit
Strongly recommend i-orp, drilling down, to see the tax implications of withdrawing from tax deferred vs taxable accounts, the impacts of Roth conversions, etc.
I-orp is an interesting starting point to get a feel for some trade-offs, but I would be very careful about relying on it.
It calculates IRMAA based on the current year income, not two years prior, so it is going to think you can make large Roth Conversions at ages 63 and 64 without IRMAA costs. That automatically means its Roth Conversion plans are not accurate.
I haven't checked, but doubt the tax module was been updated for Secure 2.0? If not, the RMD age is wrong. Last I checked, ACA was also used as a cliff, not a slope. Higher income provisions like NIIT are not included either. (I-orp was down as I'm writing this, so couldn't check my memory on these).
People also misuse it. Most folks are not really looking to spend every dime, that is far too risky. But the rapid spend down drives the entire plan. If folks don't find the entry for the desired estate value, they will get a silly answer.
Trying to leave an estate and limit income in some years for ACA can lead to convergence errors, so you may not get a result or worse, you may get a result that doesn't add up.
The most dangerous item to folks' financial health is if they enter anything for asset allocation other than exactly the same allocations in all types of accounts. Folks that enter a larger stock allocation in their Roth than their IRA will find I-orp tries to empty their IRA through Roth Conversions at lightning speed - not because it's a good idea, but because the program sees the higher return in the Roth account so wants to load that up. In reality, the program is just chasing the higher stock allocation you told it in the Roth, that dominates vs. Roth conversion economics. Before I understood this, it would tell me to do a $million+ conversion in one year which is ridiculous as we will be around the 22-24% bracket if we even things out. I've seen at least one or two newbie posters tell us they did nonsensically huge conversions as a result of I-orp runs.
Like any tool, it has uses and it has its limits. Because folks that are very inexperienced are often sent to I-orp first, they are prone to make errors and may not be able to spot problems. I would tell folks that want to do it themselves to check with multiple tools and if there are differences in results, don't take any action with their money until they understand what's going on.
For folks that don't want to learn all the ins and out of the tax code, I think a one-time-fee-only planner can be a real help.