I've used most types of plugs with no prob's, but at the end of the day, the repair is temporary and is designed to get u to the nearest place of help where an internal mushroom plug can be fitted.
Like any tight hole that ur going to shove something larger into or to give a good reaming, u should use lube suitable to the job!!
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Some plugs use a glue that also doubles as a lube until it dries.
A couple of years ago we tested various "temporary" puncture plugs at Eastern Creek on my RSVR Factory, we couldn't obtain a 300kph run down the main straight, we were probably around 30kph shy, however, until the tyre was destroyed I had no problems in anyway with any of the plugs we tested, this included string type plugs. Some are straightforward to fit others can be a little difficult the first time u shove them in. Besides carrying a couple of cannisters I also carry a little hand Pump, which saves u waisting all ur cannisters.
So it comes down to Personal preference and what type of puncture/object is stuffed in ur tyre. Splits/cuts are the worst for roadside repair and sometimes a tube of superglue can help save the day!. It also helps to stay out of the breakdown lane on the freeway or the centre of a lane where debris can be laying for the unsuspecting motorcyclist.!
Cheers,
Tex & Bundy