I have not tried the Dunlop Speedpick, but I’ve seen some images of them.
Couple things I really like about the 6mm pick. For one, it’s surprisingly comfortable to hold. Seems much easier to grip a big thick pick VS a more traditional slim one. Second, just like the Sik Pik, the distance from string to string is reduced due to the size of the pick.
The string distance being reduced is why I loved the Sik Pik so much. With the 6mm Gravity Pick, I still have the distance reduced, plus greater accuracy.
The beveling on the Gravity Pick really helps to just glide over the strings.
I found this pick on Sweetwater. I just ordered a bunch of different picks they had available. Had they offered the 5mm Primetone I would have tried that. Sounds like I would like it!