The handful of electronic boost controller installation manuals I have read call for 6 mm ID hoses for both top and bottom wastegate ports, but my setup seems to be bottlenecked with 4 mm ID hoses.

The fittings on the wastegate aren't even big enough for 6mm hoses.

How important is hose size for external wastegates?

Is it fine as long as the hoses don't pop off? Is this mostly an issue if you're increasing boost well over spring pressure?

I only learned yesterday that my boost controller actually works by using the top port to force the wastegate closed, rather than restricting boost to the bottom port.
Rather counter intuitive...

 

It doesn't matter

 

Thanks. That is what I thought...