there really isn't any risk, its safer and you get more bang for your buck. It's not as intense but there's more of a "rush" then oral but not like snorting.
Positives if plugging are longer high, faster come up then oral but slower then snorting(about 5 mins of lying down and 2-3 of walking around till it hits you),less damaging when having to ingest large amounts of tylenol because its absorbed very poorly when plugged(the tylenol).
If you want a rush(i'm gonna say your doing roxi for this example and say it takes 3 pills to feel good) you would eat one, snort one, plug one. Plugging and oral are the best bioavailabiltys, absorbing the most drug but the rush isn't really there. Snorting there's a rush but it doesn't last as long. For best results mix up your roa