XT-4 IBIS performance with different focal lenght lenses

[Jeroen Pasman Photography]

First of all i like to express how happy i am with the XT-4  .  I use to own an XT 20 and i really like this small camera but a few things make me save money and buy the XT-4 .  

I have an interesting question for you XT-4 users and its about the IBIS system.  

I am using Manual lenses only.  the AF and lens communication is turned off in my body.  I use the manual focus on the lens, the manual aperture and manual ISO.  my shutterspeed is in A most of the times but when i need a certain shutter speed than i will choose that as well .. 

All my lenses are PRIME .. i dont own any zoom.  

My list of lenses:  

12mm Samyang  F2.0  //  21mm Kamlan F1.8 // 35mm Samyang F1.4 //  50mm Kamlan F1.1  version II  // 85 mm Samyang F1.8  //  105mm Vivitar F2.5 Macro series 1  // 200mm Vivitar F3 series 1 

Now, there is a lot of info to find about how IBIS is handling Fuji lenses and how many stops you can gain by it.  

My question is this.  with what lens will IBIS be the mose usefull ?  Do i get a real benefit from IBIS using my 12mm lens.. ore will it perform any good at 200MM ?  there are 6 slots in the camera to preset my lenses ..i have 7 ......  so what lens should i not put in the preset list since it will barely benefit from the IBIS ?  

What can you say in general about the IBIS in the XT-4  with manual lenses ? 

Thanks in advance for your answers.