Why do you need to drill the hole bigger Per? The plugger kit doesn't require the drilling that you mention, and to my knowledge, they don't recommend tubes in 180/55-17 tyres? Sounds like a local thing, perhaps? 
OK, 180 might be too wide. I thought we were below 150.
The tire plugging guys at gas stations had a sharp tool they used to drill hole, quickly followed by the rubber plug pressed in with another tool. The hole after a screw or nail had to be widened Maybe they used a glue. Cut the stickout and fine to go. 5 minute job they charged $15-20US for.
No goo sprayed inside the entire wheel.
This was the old tech 15 years ago and decades earlier.
Yeah mate, you don't put tubes in modern bikes with wide, low profile tyres unless they're old school spoked wheels, so you don't have a choice. Well you do, you can drop $260 (AUD) for a new tyre every time you go over a nail, or you can use a plug. Tubeless tyres were developed to stop the incidence of blow-outs where the tube literally explodes inside the tyre, blowing a section of tyre out, and causing an immediate deflation, which can be deadly. Tubes in modern hyperbikes would not be a good idea. A tubeless tyre will slowly deflate, rather than immediately go flat.
Re: "drilling", I think that's a language thing, the tyre shops use a "reamer" or a "rasp" to clean the hole out before they install a plug, this doesn't increase the OD of the hole, it just ensures a "rubber on rubber" interface to better seal the repair. I used the water based slime not to seal the hole, but rather, as I was doing 1000 mile weekends at the time (riding from Canberra to Melbourne and back) I wanted some insurance that I wasn't gonna be sitting on the side of the road with a new nail or screw in my tyre.
I had a tube blow out on an Army XT600 back in the 90's, was riding on the freeway @ 60 MPH when the rear end went screwy, my mate John (on another bike) was pointing to the carnage as we slowly decelerated to the emergency lane, I'd had some experience with blowouts in Army Landrovers back then and the trick was not to panic, just gradually slow down to a halt. The tyre was still intact but a can of "Finilec" (tyre sealant/inflator) proved useless, just bubbling up through the spokes, but luckily a local business owner volunteered to load it into his pickup and store it there until we could collect it.
I was just happy it was a rear, and not a front, I bought the remains of a CB750 that had a front tube blow out when another mate was riding it across an old wooden bridge @ 60 MPH in 1979, which destroyed the bike, and almost killed him. There wasn't too much left that was still useable...........
