Thoughts on ISQ/BAM/ECP?

Wonder if any of you have insight on I Squared / Brookfield / ECP? Mainly about interviews, how technical are they? classic PE or more of the project finance type of stuff? I’ve never interviewed with anything that is infra specific before.

About culture, I know that all three are sweatshops, but any red flags that you know about?  

Also thoughts on comp? I know BAM might be the lower of the three, but do you have any specifics on the other two? 

Thanks in advance