If I'm not mistaken (might be), how it should work is your Pony loras probably will work, BUT they'll be less effective/compatible. May be able to make it worth by adjusting the weights depending on the lora? Others might just not work at all as they are intended to.

I have done some testing with the newest version of this model and a lot of Pony loras still seem to work! For that matter, SDXL do as well. Especially stuff like slider loras and even many style/theme ones are highly compatible. Concept loras maaaaaaay be a little less reliable, but you can probably find some prompt-based workarounds.
Illustrious is inherently very good at prompt adherence, so a lot of concepts that must be reinforced with loras on Pony, work out of the box on Illustrious. Despite still being in its infancy, community sentiment indicates that it does provide a solid base to build upon.

Soooo I suspect that if a concept isn't handled by either Illustrious finetunes or any loras, it's probably a matter of time before someone tries to tackle it.

@PrincessFruit how far this tuned model is better than original illustriousXL ?

@amazingbeauty It has a nicer default style... and that's all I can determine, because all the technical stuff flies over my head @.@ Sooooo I guess it's a matter of testing your specific use-cases and deciding whether it works for you.

@PrincessFruit ... ok (i'm CPU user)