I just bottled a Cabernet Sauvignon using a combination of plastic corks and plastic stoppers. I have occasionally had wine leak a little through the regular corks, and while it didn't appear to affect the taste, I didn't like it so I thought I would try the plastic alternatives.
I read through much of the discussion on plastic corks, although much of it is a few years old now, so I imagine that the products may be better, and the medium term storage (i.e. the maximum life of wine kit wine) evaluated.
The stoppers were white plastic and I was able to push them into the bottles by hand. I was told that they were reusable a few times. These were not the ones with the large top for champaigne bottles. The top is similar in size to the lip of the bottles. The other ones were cork shaped and light brown in colour, and I inserted them with my double-levered corker. It seems that the cork shaped ones make much more contact with the glass than the fins on the reusable stoppers. I was wondering if the quality of the seal is appreciably different between the two. I like the look of the cork shaped ones, and haven't tried to remove either yet, but the reusable ones are quite convenient.