First Radious mod i used was Rome 2 Total War. And it was an utter MOST HAVE in that game. Rome 2 campaign AI was utterly broken and didnt manage to pose ANY threat at all as they barely recruited any units or conquered bigger landmasses.
In WH1 however i did not like the Radious mod very much. Sure Radious says the game is getting harder but in my opinion it got a HELL lot easier. You got a massive economical boost back then and Elite units upkeep got more than halfed. Sure the AI also gets those bonuses but guess who is 100% able to handle those bonuses better?
In my experience the ai is only able tho handle 2 MAX 3 stacks efficiently against u. Even if they have 5 or more attacking you they just dont use them very sensefull and you mostly just have to battle said 2-3 stacks. The rest would go to another frontier or come in waves or seige settlements without ever trying to actualy attack them or what so ever.

One of the things that really create some difficulty in the Game is the fact, that even in lategame when u possess like half of the lustrian jungle, you still only can affort 5ish armies of mostly low-medium tiered units with only a very few high tiered units per army. So several waves of 2-3 stacks at several frontiers already are creating a lot of threat simply because you cant send 2-3 armies to every frontline. It really creates the feeling of getting overruned from all sides without haveing the manpower to defend everywhere. For me seemes like the game is balanced around those not-so-ultra big battles that the AI can handle half way on the strategy map whilst throwing enough debuffs on your economy to compensate to compensate for their mistakes.
When youre able to affort 3 or 4 armies more, stacked with elite units (and that is conservatice from what i have seen in WH1 Radious mod), you are going to have a way easier time even if the Ai has more available units.
Additionaly i think elite units should be exactly that: Elite. I like that i have to stick to medium tiered units as the backbone of every army even in the lategame as it is just logical and realistic. When Elite units are beeing that cheap (also and most of all relative to low tier units) there is just no sensfull reason to not go full elite on like every army. As if there were like 25 dragons, Hundrets of Dragon Knights and thousands of phoenix guards available fighting the war while the normal soldiers are enjoing adventure holidays in the lustrian jungle as they are not needed. That totaly "kills" the Warhammer atmosphere and lore.
So yeah since there are almost no sensefull reviews about the mod ill just ask here:

TL:DR
Is the game (especialy lategame) balanced and somewhat lorefriendly? Or do the changes allow you to just stomp enemies with full elite-unit stacks whilst normal soldiers and medium tiered units are not playing any role anymore (bc of relative upkeepprice and bigger income).