I have. They all seemed to work fine. I used the one actually called DNS Jumper, as well as QuicksetDNS and I think another. My needs have changed and I haven't used them in a long time, but they provided an excellent solution when I did need them. Some are more finicky to set up than others, but nothing major.

How do ISP's/Telcos feel about non-specific (to them) DNS being used?

Would their over-the-wire resets and updates cause routers to revert to their own DNS settings?

DNS Jumper and related utilities change the local DNS settings of the device they are installed on. This just saves the hassle of having to do it manually. I don't know why this would affect the router.                                                                                                                                                                                                  

The main downside to not using your ISP DNS server is for Akamai served content and other ISP CDNs.

Akamai uses the DNS server that sends them the request (ie the ISP DNS) and directs traffic to the ISP CDN node based off that IP address.

When you use another DNS provider or the root DNS servers then you would often get a non-optimal / offshore Akamai CDN serving your content. It all should all work just downloading Akamai files (such as Microsoft patches or watching Lightbox videos etc) would go a lot slower than they should.

Ive used it for a few years now for switching between dns4me and getflix or back to my default. It just works and its quicker and easier then changing them manually in settings.

BarTender:

 

The main downside to not using your ISP DNS server is for Akamai served content and other ISP CDNs.

 

Akamai uses the DNS server that sends them the request (ie the ISP DNS) and directs traffic to the ISP CDN node based off that IP address.

 

When you use another DNS provider or the root DNS servers then you would often get a non-optimal / offshore Akamai CDN serving your content. It all should all work just downloading Akamai files (such as Microsoft patches or watching Lightbox videos etc) would go a lot slower than they should.

 

upside is many of those things are moving towards anycast... Helps a ton with load-balanced connections ;)

I've used DNS Jumper in earlier versions - the latest is 2.1 - and it is a good basic DNS switcher of which there are many - I've seen at least forty over the years.
https://www.sordum.org/7952/dns-jumper-v2-1/

Google Namebench was a more comprehensive option but it is now deprecated - last update in 2010.
https://code.google.com/archive/p/namebench/wikis/News.wiki

Gibson Research DNS Benchmark was the best for comprehensive testing.
https://www.grc.com/dns/benchmark.htm

If you're interested in knowing more about them then look at this 2014 article which has DNS Jumper 1.0.6:
https://www.techsupportalert.com/content/how-find-best-dns-server.htm