I've never saved the data as a separate text file. I've always set up my systems to make and keep multiple backup copies of all the files, pulling one file a month out of the daily back ups to keep indefinitely on a different machine on a different location.
I do understand the logic behind the text export, I've just not seen the "cost benefit" work out in favor of it once the file get very large. Merge, is recommended, BTW, because it's and easier and safer format to use when importing the data back into a clone of your file. With a merge file, you can specify "matching field names" to realign the data with the correct fields.
I've built up so much data along the way, I now, when I export have over 300K of records in a table with some fields with pages of information, in terms of word count. I did a .csv and it came out just over 1GB.
I have got used to the text export as it's nice to see the data in Excel format, and I also get the logic. The problem is is that now the text file is so large I can't open it, so I've no idea if the file is okay, unless I spend extra time making a new FM file just to import and view the data looks okay.
I will go with your advice and just back up monthly whole copies of the database, and also do it the other way with .mer file extension.
With some data sets, you can back up progressively. You can generate a new text file at periodic intervals that only contains the data that is new and/or modified since the last "dump". But that raises it's own host of complications if you ever needed to pull all that data back into a clone and that's where I find the slightly better security of the data dump outweighed by the problems getting all that data back into the file should I need to...
Yes, basically, the way that you do it is the way I've always done it before reading that advice about making clone separate text table copies. I'm doing both now, but it's far easier, in my opinion, just to copy paste your FM file at the end of the day and stick it in a folder of the day.
But I would definitely support the idea of making clones (empty copies) of your files in addition to the backed up copies with data.