My Santi e.Motion came with the system installed from the factory.
The ring doesn't seem to interfere with my harness. I'm not even sure if the harness sits on or off of it, but I don't notice any discomfort underwater. Above water, I feel the straps pushing down more than with my old compressed neoprene suit that did not have a ring, but I wouldn't say it's a problem.
The ring is not gigantic, but I have a pretty big head and I'm able to get it through. The hardest part is pulling the ring over my head when doffing the suit but it is manageable.
I'm up to 26 dives since I got the suit last July (it had to go back to Santi to be recut for about 3 months of that) and the seals are holding up.
Unfortunately, it does impede my ability to reach my valves. It seems to be a problem for people with narrower shoulders, but for somebody with a wider build I suspect it would be a non-issue. I'm 6'1" but wear a size medium t-shirt for reference.
I'm convinced it's a lost cause for singles but for doubles, I'm at least able to touch all 3 knobs. I'm still working on being able to completely manipulate them (just started in doubles a couple months ago), so I'm still hoping I won't need to have the ring taken out. We'll see. The silicone seals are so much more comfortable than latex ones and being able to change a seal yourself in a couple minutes is pretty awesome too.
---------- Post added April 9th, 2014 at 09:48 PM ----------
Also, you've probably seen this post about Santi not recommending the system on the e.Motion:
http://www.scubaboard.com/forums/ex...ne-vs-neoprene-wrist-seals-2.html#post6948970. When I asked the (now no longer) US distributor about this once my suit was being sent back to be recut, they said they only don't recommend it for smaller framed people.