When I was briefly playing the game at a 4k resolution I used this mod pack with the medium icons iirc. Made a huge positive difference, vanilla faf, at least at the time, was pretty rough in 4k without mods to fix scaling issues. I thought I saw somewhere that it’s better now, but not sure I’ve never bothered to test it on my 4k monitor since I only use my high refresh 1080p for games. Going back to 1080p I stopped using it at all because I didn’t feel that it really helped. If I weren’t lazy I’d take the nuke and smd icons from it and only use those.
Honestly I feel that part of the reason some of the really strong players don’t like it is that it’s an eyesore when you’re not used to it, and they’re so used to the stock icons and so used to deciphering what they mean, or more accurately counting them really fast, at a level and accuracy us plebs don’t match. I believe it was blackheart who had some screenshots showing how it’s harder to count groups of low numbers of t1 units which is really important information in mid/high level ladder play. That’s a really big con, but I think that’s the only actual practical con.
Edit: Basically if you like it and aren’t competing at a high level and don’t want to get there then use whatever makes you happy. I can’t see this being so detrimental that you can’t hit 2k global and 1.6k+ ladder, but I do see why it’s not great if you’re truly wanting to optimize efficiency in fights and in terms of keeping down clutter.