Thanks for info.
My usage: 70% - web browsing, reading a lot of documents, statistical software, office software.
30% - DAW software (audio production).
Is it noticeable difference between 965 mb/s and 430 mb/s?
The Icy Box enclosure looks like it would have decent passive cooling, probably sufficient for what you are contemplating using it for. A boot cycle is going to be through fairly quickly, so it might heat up, but thereafter it will cool down again. Web browsing generally does not consume a lot of CPU, if you keep the tabs down (and use one of the more modern browsers that throttle the inactive ones). Office software is usually pretty light loads, at least past launch and some formatting/conversion stuff, or big spreadsheets with database hooks.
I guess one question to ask is if your particular Mac setup can support Thunderbolt, and if so which variant, as this can have speed advantages generally over regular USB-C type attached storage. An example of a Thunderbolt supporting external drive would be the:
Portable SSD X5 Thunderbolt™3 2TB
(Samsung is a pretty good make for NVMe setups, anyway, but they might be over-charging a bit for this one)
There are Thunderbolt supporting external enclosures for NVMe (including Active cooling, if you decide you need that), you could kind of put your own together, and the faster interface speeds are going to mean faster boot and other times. PCI-Gen-4 based NVMe is starting to show up, too, that is at least theoretically faster than Gen-3, but you have to also watch the buffering and R/W speeds, some of the higher density NVMe (QLC, etc.) can be slower in terms of write times, so newer/bigger is not necessarily faster (same as with hard drives, actually).
I kind of wish Thunderbolt and the USB standards would converge some, so this was a bit more standardized, seemed like that was going to happen some for USB-4, but for various reasons it might have to wait for USB-5. But that all said, there is something to be said for internal Apple SSDs, the I/O controllers are generally pretty fast, frequently faster on MacBooks than the equivalent PC variants (Samsung or otherwise), granted Apple pricing is way above what it costs for the parts, so bigger SSDs get pretty expensive pretty quickly. It is how Apple makes money from those that have the money, helps differentiate lower (smaller SSD offerings) from higher end offerings on what are otherwise very similar devices. And with internal SSDs, you have the fans to cool them better (granted, I have not seen Apple get very sophisticated yet with heat sinks or pipes, something you see on gamer PCs some).
