breech plug options

[WestTn Huntin man]

I am getting ready to order my new KP1 . I have 2 options for breech plugs. Both use 209 primers. One uses just a 209.The other uses a 209 in a plastic jacket That is completely waterproof. I have no experence with 209's. I have used musket caps for years.Anyone use a Knight or other M.L. that uses the waterproof 209's ?? Are they easy to use,load ,ect??Are the jackets very expenisve ?? Not sure if I should get one or the other or both. I plan on going thru a few rounds. My guess would be I be able to shoot alot cheaper without the plastic insert ??