Cado Royal System vs. Nelson Omni/CSS  

Surely there must be some...
Surely there must be some comments, opinions, anecdotal information about the differences in the wall units. Thanks.

royal cado the best ever!!!...
royal cado the best ever!!!! heavier than the nelson, build on and on.

I think it depends on how...
I think it depends on how you intend to use the systems. I've got an Omni, and it can be really hard to find parts for it. The brackets that were used to mount the cabinets to the poles have been known to fail (whether this is due to improper installation, or just due to the fact that the brackets are bakelite and time hasn't kind to them, I can't say). I've solidified things on my unit, just as a means of easing my mind, but the thing does make me nervous. I don't own a cado system or css, so I can't speak on those.
Have you considered a String wall unit (designed by Nisse Strinning). It's not the easiest thing to find in the US, and typically commands a somewhat higher price here, but they do pop up from time to time. Unlike the Omni and Cado, the shelves are SOLID wood (veneered over white pine). It's a solid system - really high quality. I want one bad, if you can't tell 🙂

I have had both Nelson CSS and cado
I have a Cado wall unit currently in my home and have had the Nelson CSS. I loved them both for different reasons.
CSS-
Pros-
so sleek!
so many components you can buy- amazing lighting, desks, tables, shelves cabinets, chalkboards etc etc.
CONS-
-so. many. pieces. the shelving hardware is fussy- too many small pieces- you lose one small bolt and you will be paying $30 for a replacement on ebay.
-installation can be a pain lining up all of the in rail brackets that hold up the components- would be difficult to install if you bought it without seeing how it "goes" together (like off of ebay) without manual
-wood veneer on my shelves warped and cabinet fronts bubbled and had to be fixed
CADO-
PROS-
so stunning
beautiful components- desks, display shelves, chests of drawers etc
relatively easy to install- intuitive design easy to figure out how to install it without manual
CONS-
doesn't hold a lot of weight- records- books
Overall- I like my Cado more but of course that is my personal preference. Whatever you decide you will still be getting a stunning conversation piece.

Omni and Cado (or Cado-esque)
I have a walnut Cado-like system installed on my family room walls (I'm still not sure who designed it, after much research). The pros are that it's gorgeous. I configured it to frame my wall-mounted flat screen, which is 60+" and it looks great. The cons are that it's time-consuming to install. Not difficult, mind you, but time-consuming. I had to make sure to get the wooden strips positioned correctly on the walls--plum and level. When I got a bigger TV I had to re-position the wooden strips to accommodate, but that was just poor planning on my part. Another pro is that the hardware to attach the pieces to the wooden strips on the wall is one "U" shaped metal bracket for *all* the pieces. Simple and easy to manufacture if you need more (the wooden dowels for the Cado are similarly simple; I also have a Cado that I don't have room to install. I know--not a bad 'problem' to have).
I also have an Omni unit. The cons have mostly been mentioned. Finding the right hardware can be a challenge. There are different versions, which can be confusing. I have collected a few different instruction sets, which is helpful. But the instructions are sparse (to put it kindly). The bakelite bracket breakage is primarily due to faulty installation, but I can definitely understand why it happens--the instructions for installing these are virtually useless. I had to logic it out by looking at it carefully and turning it over in my head for a few days. Not ideal, as my head ain't that great. The pros: extremely flexible, looks great, endless configurations (including corner turns), and easy to make cool shelves and cabinets on your own. This makes it better than the Cado, IMHO. But I love them both. Hope this helps!