It's just the same useless argument every year. Just use what you want. I've been taught pi since secondary school. I understand it well and can use it effectively. Never have I sat there and thought, "if only there was a shortcut to multiplying this by 2". There's whole sites, videos and movements to get tau popular. I just personally don't understand the point.
That's exactly the issue. You are thinking in terms of pi, so it might be hard to see from a different perspective. It's like using a slightly off abstraction for a concept. At first you have to make a small effort to hold it in your head, then at some point it's committed and you can manipulate the concept directly.
Do these phrases attach themselves to the real number, or to the expression language? If the latter, do you say two number-expressions are equivalent if applying some normalization function yields two equal expressions? Do you consider two number-expressions distinct if they evaluate to the same real number, but cannot directly be related to each other?
For example, let:
S = { (x, e^(ix) + 1) | x in R, x > 0 },
T = { x | (x,y) in S, y = 0 },
c1 = min(T),
c2 = 6 * sqrt(sum(n^-2, n > 0))