The differences between the official and unofficial versions are so significant that the differences between the versions themselves are smaller. So why mix them?
If

2ZYbr
The point is not that Equilibris is "better" – it's a balanced (as much as possible in Heroes) version specifically for online play.

– then it's even more unclear why you need to switch to Equilibris in offline mode?
Catch has already talked about this.

I can't assess the usefulness of certain Equilibris features for online play. But for offline, their positive side is not noticeable, and the concept of "balance" is almost meaningless for offline. The negative effect, however, is significant – the need to remember which version a particular feature works for, and how exactly it works.
ZYbr has already spoken about newcomers. And, please, don't filter out newcomers based on the criterion of "they will only play a couple of maps" – they will all be filtered out. Including those who, under more friendly entry conditions, would have played, gotten hooked, become interested, learned, grown – and then they could themselves choose whether to switch to Equilibris or whether "the best is the enemy of the good."

The most significant advantages of Equilibris for offline are that the swamp slowdown has been removed, and the experience gained in a battle is displayed explicitly. Yes, that's useful. But I can't recall any other noticeable improvements, maybe I forgot something.
I'll note one serious drawback – there's no attack by pressing Enter. This really hinders when selecting a field for a battle.
The bugs that Equilibris fixes, according to Lu's description, are good. Only, I'm a slowpoke, I didn't even know about these bugs, I didn't encounter them or didn't notice them – well, they don't interfere in offline mode. And those that do interfere remain in Equilibris.
At the same time, they added new errors, as if there weren't enough old ones:
- does the enemy drink an immortality potion before the battle? Okay. But how many times, and from where?
You attack, kill, the immortality effect triggers, you run away/lose. You attack again immediately, but the immortality effect is still active on him. And, moreover, his pockets were empty. That's annoying.
- when selecting a field, mana is drained from the staff. Apparently, the value is not always updated when loading.
- in battle, there is a counter-attack with a shot in response to magic.
- the morale calculation in battle is buggy.
There are other issues, but I'm too lazy to write, it's not interesting.

Well, you don't understand much.
By the way, we strongly request that the new release also include the ability to write cheat applications and the checksum of the save file.
Is that also unnecessary?

Yes, I don't understand much, and I don't hear answers. And now it's still unclear.
There is a key question – will this information be available for reading to every player, or only to particularly important ones? Last time, the developer answered this question incorrectly – he put users in unequal starting conditions. Or, if that's the case, then state it directly in the documentation: the program was created by order of so-and-so and so-and-so, and it works exactly in their interests, as they understand them.
The same applies to other, more abstract terms:
The program has functionality hidden from the user, which is not needed for normal operation and is not an error or garbage. It consists of collecting certain information about the end-user's operating modes. This information can be used by third parties, and a well-intentioned user usually does not have this possibility.
- Am I understanding this correctly?
Because it already looks like a description of some kind of Trojan. It's time to write recommendations to run the new Equilibris only on a virtual machine, after backing up to an external drive.

Catch, the position is clear. Let's have races on broken-down cars. What? It's more accessible, closer to the people.
...
Maybe you just don't know how to prepare it? ;)

They are. It's called "monoclass." And there, it doesn't matter if it's a Lada or a WRC, the main thing is that everyone is in the same cars, in equal conditions, and only skill decides the outcome.
And it never happens that the judge races in the overall standings, but in a slightly different car, because it's "necessary for his position" :D
- this is about the ability to prepare

Although I tried it here. I remembered about the infinite poison and killed, like, 150 thieves with a level 1 hero and an imp. I laughed.

I doubt there were no other conditions... How did you run away from the thieves, especially from two squads?

And whether the poison is infinite or not – that's a minor issue. There are countless battles in the fourth game, and the vast majority of them are present in Equilibris. Removing them would be a different conversation.