The icon mod does not provide a gameplay advantage, and very likely is actually detrimental to your gameplay.
Every pro at the game either uses all default icons or mostly default icons, and the chance of the icon mod providing a gameplay advantage is slim to none, given that the pros are the best at the game precisely because they are the people most likely to take advantage of things that can provide a gameplay advantage.
As a counterexample, look at the advanced strategic priorities mod. Almost every pro uses it, and some of the very best have gone as far as to set 10+ target priority hotkeys on the most premium hotkeys. That is what would happen if the mod actually provided a gameplay advantage, so it's almost impossible that the icon mod provides a gameplay advantage and all the pros are just all sleeping on it.
If it were the case that using full icon mod was is a matter of personal preference, with no gameplay impact, you would expect some pros to use it. The fact that literally no good player uses the full icon mod should suggest that it is actually a gameplay detriment.
My personal view is that you can use whatever setup you prefer and play the game the way that you enjoy, but just be cognizant of the fact that using the full icon mod very likely provides a gameplay disadvantage.
I'll just list the people I'm aware of on each side of the debate. As far as I am concerned, there is an overwhelming consensus among experts on this topic.
People who use full icon mod:
- Ruvik
- Katharsas
- Wainan
- Cheeseberry
People who use mostly default icons (only advanced SML/SMD, etc.)
- ThomasHiatt
- me
- Tagada (when he gets around to it)
People who use full default icons:
- Blackheart
- JaggedAppliance
- Blodir
- Swkoll
- and literally every other top player in the game