You can't AFAIK but I've not found it to be an issue. Maybe I've been lucky with the hardware flash chips on my boards. I've got Wemos D1 mini clones and NodeMCU boards all of which are a couple of years old now.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Yes, cool flasher, afaik there is no way to figure out if you can use qio or have to use dio, which is slower.