A-Win Premier conversion to Q-Mac - does it work? Want a Mac M1 processor

The problem with any definitive statement is that "your milage may vary". Many Quicken Windows users have successfully migrated to Quicken Mac with no problems or a few minor hiccups, but some have hit significant roadblocks.

The biggest obstacle for some Quicken Windows users is that investment transactions of the BuyX/SellX variety aren't imported correctly. Quicken Mac doesn't support the combined action + transfer, and requires separate transactions for Buy/Sell/Reinvest and for transfers to/from another account. I don't know why this doesn't import correctly, as it seems pretty straightforward, but users report it doesn't. Depending on the types of entries in your investment accounts, you may have a little or a lot of clean-up work to do to get your cash transfers properly in place in Quicken Mac. (If you're able to run Quicken Windows and Quicken Mac side-by-side, it helps this clean-up work go more quickly.)

And there are other things which don't import. You will have to set up your reports from scratch in Quicken Mac; the same is true for budgets. If you have attachments in your Quicken Windows file, they will not import into Quicken Mac. (Since you have a large file, I'm guessing you may have some attachments.) For some users, these are only minor inconveniences, while for others, they're significant obstacles to be worked through.

And as noted above, this is pretty much a one way trip: going from Quicken Mac to Quicken Windows is even more incomplete (investment transactions don't transfer), so you should consider running in parallel on Windows and Mac for a short while while you make sure your data in Quicken Mac is sound, with correct account balances and investment holdings, before you cut the Windows cord entirely. 

I've read a less-than-a-handful of scattered reports of people with very large data files not getting their data import complete because the Windows exporter seemed to choke on the size of the file. I don't know whether this has ever been officially confirmed; many thousands of Quicken Windows users have converted successfully, so the odds are that you will, too. It's just not something anyone can state with 100% certainty until you try it with your own data.