Philippe,
The issue with 32bit textures is that the FS engine was just not designed for them. The fact that it can display them does not mean they should be used.
Its all about performance.
I'm not going to attempt to change anyone's mind, you're free to use whatever format you wish to, and clearly after so many years people have entrenched positions.
However look at a vanilla FS9 install. you will not find a SINGLE 32bit texture. ACES never designed the FS engine to handle multitudes of these textures and the VRAM they gobble up.
Now in FSX things are slightly different because it was designed at a time when 1GB+ graphics cards were becoming common and the graphics engine is far more refined than FS9's. That said again look at a vanilla FSX install and you will not see any 32bit bitmaps there. The preferred formats in FSX are DXT5 and DDS.
Having had my system worked over by FS-GS, one of the most important things I was told was to convert any 32bit textures I had. I did and the performance difference was significant. I always laugh when people complain on forums about blurries or stutters and then see screenshots where they are using HD 32bit textures on aircraft and the like!
One example I was told about was regarding VC textures. Did you know that FS is rendering these textures even when the VC is not displayed? Yup if you have a bunch of 32bit VC textures FS will still be rendering them even when you are in spot plane view. Throw in some HD 32 bit aircraft textures then some 32bit AI textures and 32bit scenery textures and then you hit stutter or blurry land. I always convert VC textures to DXT.
Like I said, not here to to persuade anyone, simply passing on information. Ridding my sim of 32bit textures and adding mip maps was the single biggest performance imporvement I got in the sim. Of course you need your cfg settings and Nvidia Inspector settings set up appropriately as well, but I don't get any mip blurring or shimmering, and silky smooth performance in all phases of flight and all views.
IMHO 32bit textures for AI is total overkill. I find that for flying purposes I'm never close enough to any AI aircraft to spot DXT compression and for me the tradeoff between a slight quality loss but significantly improved performance is well worth it and I'm sure Mariano agrees after he did the same thing. Infact I believe he even went to DXT1 with his AI textures.
Again, I respect everyones right to choose and set up their sim as they see fit - Its the beauty of our hobby, this is just background info
Cheers
Garry