Definite Keepers!!
Three of us just added X-Chairs to our offices and are happy to have done so!
We chose the "loaded" version all around. The roller style FS wheels are an indispensable add-on, not only for the delightful ease of movement but for their near silence on the hard floors in our offices. The Elemax heating, cooling and massage unit is a delight.
If I could twitch my nose and create magic, I would make it possible to adjust the headrest (also a delightful add-on) adjustable to a slightly lower position.
There was one bit of miscommunication as we sought an adjustment to one of our three chairs by changing the cylinder from "standard" to "short." My
thought was that a short cylinder would allow the seat to be situated closer to the floor than would a standard cylinder. In fact, it turns out, the short cylinder limits the height to which the seat can be raised. The lowest position of both cylinders is the same.
The mix-up was resolved with a single phone call and an instant refund. Great service all around as we made some changes to our original order then submitted a second.
BTW... Don't be put off by "some assembly required." That means inserting five casters into the base, two bolts into the back rest and one bolt into each armrest. A buddy to balance the backrest as you start those two bolts would be handy but not essential unless you genuinely do have two left hands.