So I chose this rather provocative title. Because the subject is discussed on the internet in a very non technical way:
“With 16GB you are future proof.” Well, 8GB has been the baseline with Apple for over 10 years, and will most likely remain so with their unified architecture. Pro-users will buy more memory, but these users will definitely not buy your 3 year old 16GB second hand mac. Meaning the extra money you payed for 16GB will not result in a premium second hand value. The audience for your 2nd hand mac will more likely be first time users, or those looking for a second mac. In addition, given the rate of processor development at Apple, your m3 will look outdated in 3 years time, even with maxed out memory. So bottom line, future proof is a myth.
“If you have the money, 16GB will give you peace of mind.” I would argue in reverse, if you have the money, save it on the 16GB and spend it on a 2TB Samsung T7 external ssd for time machine. Only backups give you peace of mind!
“My friends 16GB mac uses 5GB with light use”. This is about Unix memory management, which is highly optimised during the multi-user days when memory was expensive. Why leave available memory unused? If it’s there, occupy it. Does this mean a 8GB machine will run slow with the same usage? No definitely not. This has nothing to do with “large or big” applications.
Unix replaced swapping with paging decades ago. Meaning only the code and or data (structured as 4k pages) that is needed is active in memory. This is the so-called working set size (WSS) explained here. Most usage profiles run “local code”, meaning the same code parts and related data are used over and over again. Like opening a new browser tab: same code, same javascript engine etc. etc. just different content. Will you notice, that when switching tabs some content is paged in with 3GB per second? It will probably be finished before the next screen refresh. (A 100Hz screen gives you a 10 ms time slot. Assuming 1GB disk speed, 10 MByte of data can be transferred in 10 ms. Google tells me the average internet page size in 2023 is 2,3 MByte.)
Such optimisations will fall apart when processing video where a large “processing buffer” is needed. So an audio pro-user might happily run 80 Logic tracks with many plugins on a 8GB machine, where as a video pro-user processing 4k content might experience slow downs, justifying the extra money for 16GB. After all, time is money.
Finally and off-topic: “Buy the 256 of 512 GB version?” Well that’s easy, on the m2 mac mini, the 512 GB disk is twice as fast. No, it’s not some different module (as someone wrote) but just 2 x 256 GB occupying both “storage slots” and thus maxing out the bandwidth. As an added bonus, the 512 GB version is a standard model (i.e. not BTO), and thus you easily get over 10% discount on Amazon and the likes…