I don't think this notation would get confused with deltas; how it's used is pretty different, and overloading symbols (especially once you're in higher levels) is common enough.
Overloaded symbols became a nightmare in some of my later undergraduate work.
It is not the math classes where I'm worried that this would be a problem, it's in the engineering courses. There's a few situations in mechanics/structures/materials that I can think of where using ∆ instead of the existing 3 notations would become nearly untenable. In these circumstances each "line" of a solution/step usually took the form of more than one page.
