The documentation for std.stdio.write() says: "... for each argument ... format the argument (as per to!(string)(arg)) ...".  Nevertheless, arrays are formatted differently when using std.stdio.write() and std.conv.to!(string)():

import std.stdio;
import std.conv;
void main() {
	writeln([1,2,3]);		// prints [1 2 3]
	writeln(to!(string)([1,2,3]));	// prints [1,2,3]
}

I expect the formatting to be identical.