After being on the list for a while, I have noticed that we have
our own set of frequently asked questions, this being one of them
(another being on bleeding the clutch).
I don't know that we ever reached a concensus on this question. I have
used both types of jets for two decades, and I find the difference too
hard to call. The grose-jets last a lot longer but are less reliable.
Every once in a long while, they stick. The standard jet, with its
rubberized tip, makes a much better and reliable seal, but tends to not
last nearly as long as the grose jet.
Still I prefer the standard jet because I don't mind taking my SU carbs
apart every few years even if its just to clean them.