From my review, I think the isolated version is worth the (not so significant on ebay) difference. Yes its purpose is to break the ground loop rather than floating at elevated voltages (although the isolation components have decent rating). Trashing your PC isn't the best way to experience early stage learning, although they will have to understand the issue / danger of ground loops at some point. It also usefully reduces noise levels in some circumstances.
I run my Analog Discovery 2 through a powered hub. It doesn't break the ground connection but the hub, rather than the PC, provides the power.
Believe me, I think about the possibilities of destruction every time I use a PC based 'thing' including uC boards connected to off-board things. All run through the hub.
https://www.amazon.com/gp/product/B00VDVCQ84/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1Breaking the ground connection is a better plan, no doubt. I don't work on high voltage <anything>, +-15V is about my limit. No real reason, I just don't work on things that operate at higher voltage. If I want an SMPS at running off mains, I buy it!
I'm getting old and I have been using analog scopes for 60+ years including the one I built from the ARRL Handbook back around '58. So, I have a wee bit of time in grade!
I don't see where spending any time with an analog scope teaches anything that can't be learned equally fast on a DSO. There are only 3 elementary controls and they are identical: Volts/div, Time/div and trigger level (polarity). Yes, there is AC vs DC coupling and that is just as easy to change on a DSO as it is on an analog scope. Tap the channel button and the selection button is at the top of the list. Every single thing you can learn on an analog scope is equally easy to learn on a DSO. Well, 'delayed sweep' might be a challenge but that's for the advanced user anyway. I have NEVER used the feature on my Tek 485. Not once!
If an analog scope was available, sure, use it! If not, don't spend $5 buying one if the intent is to buy a DSO. Well, maybe $5. But certainly not $100. I like my Tek 485, I got it cheap ($200) and it works well. It sits, unused, under my bench since I got the DS1054Z. The DSO has features the analog scope couldn't even dream of. Measurements comes to mind! How about Single Shot? Try that with an analog scope (other than a storage scope). Single Shot is the biggest feature of the DSO and it is truly important.
Want to get started with a DSO? Connect the probe to the calibration output and press "Auto". Then look at the screen to learn about Volts/div and Time/div. Twist the knobs, see how the display changes. Now progress at your leisure. You know how to get the trace on the screen - something they used to have to put a "Beam Finder" button for in the old days of analog scopes and all it did was verify that the scope could provide a trace but didn't help find it (think high voltage DC coupled with V/div set at some low value).
I'm not sure what to think about a USB scope. Sure, my AD2 is USB based and the UI isn't horrible. I don't know how the VDS1022I UI works. I watched a short video but I can't say I was impressed. So, in the near future, I'll buy one just to test it out. They're cheap enough and I have an application so why not?
There are a lot of people taking the position that a new user should start with an analog scope. Fine! But tell me exactly WHY? What are they going to learn that isn't nearly identical on a DSO? I started with an analog scope (by definition) but now that I have had a DSO for a couple of years, I can't think of a single valid reason to recommend such a thing UNLESS the issue was bandwidth. Price wise, a used high bandwidth analog scope is going to be a LOT cheaper than a new high bandwidth DSO. But it's used... And what about measurements? Decoding? Single Shot? The analog is about as useful as a '55 Ford.