@Rocky I've had a less than stellar experience with Nomacorc, especially on bottles that got heavy duty vinyl shrink capsules and required a little more heat to shrink. The corks softened and got stuck in many of the bottles.
Also, a few bottles that were stored on the side started leaking about 2-3 months after corking. Maybe it was a bad batch of Nomacorcs, or maybe they were older than a year. The manufacturer's site says to not use them if they are older than 12 months.
I started looking for better options and found Diam, a suggestion that
@BarrelMonkey made in one of his posts, if I remember correctly. I bought a few small batches, than I bought a box of 1000 and never looked back. I give away wine to a lot of people and they are all impressed with the quality and feel of the corks I use. Diam are a little more expensive than Nomacorc if you buy them in small quantities but they don't have an expiration date and are just as good for many years, if bought in bulk. I've used them in 500-600 bottles so far and not a single one failed in any way after insertion.
Again, this is purely my experience and I don't want to argue how good or bad Nomacorcs are, since a lot of people have had good luck with them. I think they work fine if no heat (or very little heat) is involved in the capsule instalation process and if they are new (recently manufactured) at bottling time.