Personally I think this is a great idea.
How did you think of implementing the halo?
White colour might work and highlight it nicely on the battlefield but there's a risk of it being misunderstood as a selected unit then.
I'm not sure if we need the land/navy unit icon since all land experimentals can travel underwater as well.
Even more I'd be wary about using the navy/land icon for fatboy and monkeylord as the torpedos on those are really weak compared to the megalith. It could give false information to the player.
I also think we could use the ingame symbols for specifying what type of experimental it is. So cross for direct fire, etc.
There was quite a bit of similar discussion in
here if you're interested. One problem that wasn't solved was how to differentiate between land/air/navy experimentals and this would do exactly that.
I made a couple of quick concept tests on how white halo would work with the current icon system in 16x16 and 15x15 size. This would be a GC, Yotha or a Monkeylord, depending on the faction.
I think the 15x15 is a bit hard to read, especially if the map texture is light but the 16x16 one works really well. I am sure the 15x15 could be made to work, the problem becomes making sure the symbol in the middle doesn't get too squashed.
TL:DR of the other thread:
Some people think they don't need new icons. Others would like them.