Had mine for six years now and just now the soft neck collar is starting to break down. Hard to beat the Zen zipper for comfort and dryness. If you can afford the Psycho III (aka Freak) I find my 3.5 far superior to any suit I've owned previously. Generally very dry and warm even on the coldest days. The first to go is always the feet and the hands. Hard to get a good seal going with boots and gloves. For the record, I've had O'neill gloves and Xcel gloves and while the Xcel gloves are not quite as flexible, they are very warm AND they hold up WAY better than any O'neill gloves I've ever owned. No tears, no pinholes, and above all no between finger failures.
They are great suits. The 4:3 gets used the most and last me about 3 years surfing everyday that there are waves. O'neill will repair of fix anything long after the warranty has expired for free. I have all three thicknesses and wouldn't buy anything else. One comment on the new Psycho Freak; it is a heavy thick suit and I would prefer a built in hood on a suit that heavy. My 4:3 is warm enough to use all winter except on the very coldest days with alot of wind. I use the 6:4 on those days. The suits are very flexable and I've never had a rash. I can't say that about other suits I've tried.
You can't beat the customer service from O'Neil. I've had one for 4 years have sent it in twice for minor repairs. They take care of it, no questions and usually will replace anything else they see starting to wear out.