tl;wr - Stable, reliable tool. Quit messing with free apps that freeze and pay for something that works every time.
I'm really really pleased with AnyMerge. It's the most stable, consistent mail merge/records to multiple documents application I've found in the Marketplace. Those of you who are of a certain age will remember fighting with various applications' mailmerge features (FileMaker Pro anyone?). AnyMerge makes the process much *simpler*.
It delivers the perfect set of features for my purposes (running off google doc assignment sheets that I send out to a team of freelance writers). Now that I've got everything set up, I can hand the whole operation off to someone else in my department. That's only possible because of the stability of the app. It doesn't require me to hover over it as it runs. You just press select some rows, press Generate and boom 50 customized Google docs saved anywhere you choose.
Here on the Marketplace, you get what you pay for. If you save just 1 hour running a merge with AnyMerge, you've more than paid for the very easy-to-handle monthly fee. Pay the fine folks at INNOVA and get on with your life.