Hey Jeff!
Call me SeaJay. I've been around on this board for a very long time.
These are super-great questions... And I'm thrilled that you're finding the discussion useful. Yeah, it's little things like this that every drysuit owner has to learn the hard (and expensive) way... So I'm thrilled to help you shortcut that as much as possible.
1. Yes, DUI will install SiTech rings, which is great. To be able to add the Waterproof Ultima dryglove rings, you will need the SiTech QCS Oval rings. So no... The Ultima dryglove rings will NOT fit the SiTech QCP Round rings.
The hard plastic ring that makes the QCS oval and the QCP round is removed and replaced by the Waterproof Ultima dryglove ring... Which is round. So even if you order the QCS, you will end up with a round ring once you install the Waterproof Ultima dryglove ring. The hard, oval ring of the QCS system is discarded when you install the Ultimas.
The reason that you MUST go with the QCS and not the QCP is because the Waterproof Ultima dryglove rings do not fit on the rubber receptacle that is glued to the suit with the QCP rings. Yes, the rubber receptacle is different between the QCS and the QCP - which adds a lot of confusion. The QCS is required for the Waterproof Ultima dryglove rings to fit.
...So tell DUI that you want QCS Ovals installed. They'll be round once you install the Ultima rings.
For those of you reading this that have QCP rings installed, you can not use Waterproof Ultima rings and instead need to use SiTech's Quick Glove, which is larger and arguably less secure than the Waterproof Ultima rings.
...Or you can simply have the QCPs replaced with a set of QCS Ovals.
2. The Waterproof Ultima rings are DESIGNED to be used with wrist seals. They work perfectly with both seals and gloves installed simultaneously, and there is no need for any unusual trimming. I fully recommend using SiTech silicone wrist seals in this case, coupled with SHOWA 720 gloves. The silicone seals are softer and more flexible than their latex counterparts, and won't degrade in sunlight or with exposure to ozone like latex does. Unlike what I've read here, I find silicone lasts LONGER than latex for this reason. Yes, they're softer than latex, so you've got to be gentler donning and doffing... But do that, and silicone will outlast latex all day long
I simply trimmed my silicone wrist seals back (all the way to the ring) because I felt that the seals were doing me no good anyway, and I found it easier to don and doff the suit with them trimmed all the way back. I would have removed them altogether except that they do need to be present to help the rings seal properly... So a full trim it was.
...But no, you do not need to trim them all the way back as I did if you don't want to. If you prefer the extra security of the gloves AND a wrist seal - or if you want to leave the wrist seals in place so you have the option of using a wet glove - you can keep them. It works great.
