on the advice of the VAPE tech folks I ordered some peculiar NGK plugs that have three ground tabs circled around the center electrode, I test fitted on my spare Gilera head, they were a tad longish, so used three spacer washers to get installed length perfect, fitted to the bike and fired up, oddly enough engine sounds noticeably different to me in a good way.
Spark plugs with multi ground electrodes have been around for ages. I've seen them with electrodes numbering from zero to four. Of course, the manufacturers of each type of plug claim that theirs is best. But you'd think that if any particular configuration offered a significant advantage over the others, then everyone would be using them.
Er, hang on ... everyone IS using a particular configuration - the single electrode type.
I've read reports that say the extra metal in the multi-electrode type tends to conduct heat away from the initial flame as it first begins to form (flame kernel) resulting in a slower burn rate. So you may get the same result by using a conventional plug and retarding the ignition a tad. It would be helpful if Vape actually gave you access to their pre-programmed ignition curves (yes, I'm still pissed off about the conversation I had with Vape on that subject).
Also, additional ground electrodes surrounding the centre positive electrode tend to block the passage of the flame front, further slowing down the flame propagation and leading to a less reliable and less stable flame.
The impression I get from a little bit of research is that the fewer ground electrodes the better, to the extent that no ground electrode at all is ideal for the best flame propagation. Surface gap plugs (no ground electrode) were favoured by Kawasaki on their 2-stroke triples for a time. However, not having a ground electrode offers no opportunity to adjust the spark gap. The spark just jumps from the centre electrode to any random spot on the outer grounded part of the plug. I guess that's why single ground electrode plugs that allow an adjustable gap have become the default plug type.
This technical paper contains a lot of jargon and test result charts, but it seems to support the points I stated above. https://www.sciencedirect.com/science/article/pii/S2090447912000883