Behind sufficiently solid big corporate- or government-quality infrastructure defenses that can certainly be true. In this country you still occasionally see ATMs displaying startup hang or BSOD screens that are recognizably Windows XP.
Given the nature of our OP’s posts so far I think we can safely say he’s nowhere near so well-protected.
Looking it up, that is a rather underpowered system for Windows 10. It’ll run, but I would not be surprised if you had a significant performance hit. And it appears to only have 32 GB storage, which is a problem as I stated above.
This, however, would not be what I meant. The main security of S mode is in how it handles apps. You’re talking about untrusted connections, not untrusted apps. In theory S mode could help there, but I wouldn’t consider it significant as long as you don’t download apps from insecure websites using that connection.
Still, with the above specs, I’d recommend staying with S mode if you can. Thunderbird, Google Docs, and new Edge are good apps to try instead of your old ones.
If anything, I’d try upgrading to Windows 10 on the other laptop and seeing if you like it better. Ar least then you could downgrade to Windows 7 if you don’t like it.
But I’m going to guess your new laptop is more compact and portable. That’s the main trade-off with those Windows S mode machines: lower power, more portability.
I’m also curious: what is your battery life like? How long can you use the computer unplugged before it demands you recharge it?
Battery life seems really good. Starting tomorrow I will be using it exclusively for the next three weeks so I’ll know better then and will get back to you. I plan to leave it in S Mode during that time.
I don’t see Thunderbird at the MS Store though. That is my preferred email app so I hope I’m doing something wrong.
What I object to is this:
What I object to about that is that it isn’t true. Not behind corporate firewalls: not at home.
There was a time when directly connecting an unprotected Windows computer to a modem connected to the internet, would get you pwned: that time was 20 years ago. But right now, getting pwned only happens when you have specific, unusual services directly connected to the internet, or when the user engages in specific dangerous activity, most of which is equally dangerous on supported and unsupported versions of Windows. And many, many people use older unsupported versions of windows for the internet without getting pwned.
Right now, it is difficult to use the internet with Windows 98, 2000, or XP, because the modern internet requires javascript features and security protocols not supported by browsers on those platforms. On the other hand, most modern exploits are also unsupported by those platforms 
So it was never the case that it ever became more dangerous to use those platforms after support ended: quite the reverse: and the widespread introduction of NATing routers removed the biggest danger of using unsupported OS versions.
I’ve removed systems that were fully exposed to the internet, that had specific, well known flaws, and even those were unpwned. The subset of exploitable bugs that actually leads to COVID-like pandemics is quite small, and even of those, the subset that affects out-of-support home systems is even smaller.*
Which, to date, leaves many out-of-support home systems unpwned forever.
You, or anyone, can argue that a system which depends on the user not doing something wrong, is inherently unsafe. I note your profession. But that is not the same as saying that failure will happen. Actually, many users go forever without doing anything wrong, and their systems, supported or unsupported, do not get pwned.
And when it does happen, MS released a WannaCry patch for XP, even though XP was out of support. WannaCry was ineffective on Win2K, and not possible on Win98.
Cool. Thanks for the additional explanation.
As you suggest, I’m probably guilty of spouting the conventional wisdom from 10 years ago when I was last actively in IT. Which conventional wisdom has become stale as it always will.
Well, crud. I found an article talking about it being unofficially added in 2019, but didn’t actually follow the link to see if it was still in the Store. It appears it is not.
The project to convert it to an app that could run in S mode is still there, and no one reported its removal. But I did run into a post on the r/Windows10 subreddit that seemed upset it existed and wasn’t “officially released by Mozilla” despite the fact that Moziila had stopped making Thunderbird by that point and released it to the public. Their argument is not one I find persuasive: they worried the owner might, in the future, update it with malware or something, even though they had gone out of their way to make it where you could easily check its source to make sure it wasn’t malware.
They oddly chose to try and cripple the OS they seem to like. Well, some of them–there was a lot of talk about Linux and how it was okay for the various Linux repos to do the exact same thing this guy did.
Sorry you can’t use your favorite email client. Other alternative versions of Thunderbird, like Thunderbird online, seem sketchy. You’d likely be better off trying out various email clients in the store to see if you can find one that you like.
And this, @LSLGuy, the fact that it’s so hard to use open source software, is another reason I think poorly of S mode. Microsoft’s decision to not implement ways to have open source software in the store (like, say, automatic source checks to make sure no malware is included) are another reason I don’t think it’s actually about security.
@BigT…battery life is great. I’m not sure really how to quantify it though.
I’m getting used to S mode more and more. I’ve migrated to Outlook and Excel and the only complaint anymore is that they are both more complicated than they were when I last used them so its taking extra tie to do the very basic things that I want to. Thats why I liked the basic OpenOfficeCalc and Thunderbird.
Word knid of messed up my website when I used it to edit my index file so I’m using Notepad++
I still need to convert fully from DropboxS which is kind of unwieldy to OneDrive.
I can’t seem to make Google and GoogleMaps my defaults for searching and mapping. I do have Google my MS Edge page when I start up but can’t make it so when I add a tab. I’m going to look into MapsPro with Google Maps API (whatever that means) and see if that helps.
Thanks again for all of your advice!