Yes, works perfectly, I have it down to a science, if I just get the cable in no later than one second after the beep, the 15KHz or TV-only mode games will boot VGA mode. I found when playing around with my 15KHz SCART, the same applied, although now that I think about it, I think I had to boot with the VGA box in VGA mode, then remove and swap with the SCART, that was the first time I ever managed to get Mortal Kombat to work in 15KHz/RGB. (Edit--there's a really funny thread in the old forum I started the day I discovered this. [Edit edit--Well I thought it was funny.])I guess I am not harming the box or DC but it's hard to shake this collector's paranoia. Even if I weren't skittish about doing it all the time, it is still a real PITA.
Games that work with this method do not always work "completely." Dino Crisis for instance, I think that was another game that didn't like either 15 or 31KHz RGB, and it was missing a lot of graphics--the 2D stuff before gameplay was glitched or just gone completely from the display. But evidently this is a problem with how the game was made, and subsequently never tested to work in either of these modes. The usual 2D-to-VGA mode blues (blocky Giga Wing stuff) of course also applies.
I guess I should keep trying the TV-to-VGA switch method to see if it works with the Performance box. But if not, I'll have no choice but to open the box up and try installing a second switch to use 15KHz RGB. I started to attempt this before but could not trace down the circuit, I am not sure if I don't know what to do with my tester (seems likely :unsure: ) but the pins on it (tester) are pretty damn big and I could never get an isolated connect to the DC-side pins very well.
Edit #3: Who is that guy in your icon? Why does he look like Jerry Springer?