I've recently been investigating pin nailers. They use 23 gauge headless pins, whose entry holes are very hard to detect (depending on timber). Currently all models available here limit the size of the pin to 1" (25.4mm), which means if you want to pin a 19mm board, then you only get 6 or so mm into the timber beneath. Some US companies (Grex, Omer) market pinners which have longer pins (up to 1 3/8" - 34.9mm).
My question is, if you had the choice, would you by the pinner with the extra length.