Cement vs foam core boards

[Kilo]

Hi, I'm about to redo an en-suite after taking it back to the stud. I have been doing a little reading on backer boards (but clearly not enough to be sure what to use!) I have gyp-frame 40 cm studs and an external block wall that needs dot and dab. I guess a lot of people rate Hardie backer. Just wondering what professionals and DIY's alike have used and what you would rate? Ta.

 

[Trades Training School]

insulated board/ backer board all good. I use BAL board mostly. like it because you can cut with Stanley.
I always tank