There is a small savings in cost, but IMO the C1 isnt revolutionary by any means, and will ship almost a week later than S3+ units will (which is a ~$20/0.05BTC difference)
Theres a higher risk of leaks and failure with this design i think, and for most people taking up slightly less space, with a large rad dangling someplace, wont offer much benefit as the S3+ is fairly easy to stack on its side anyways.
If someone can point to a 5kW-sized radiator/pump that could run multiple C1 units in parallel for under $150 though, thats a different story
There will be some kits soonish for multiple units, but generally you can't put 5kW of heat in an arrangement like this [easily]. Coolant temps would be too high by the 5th unit, and the head pressure required to go through 5 sets of waterblocks would require pumps in series which is never a great idea. Remember the tube cross section is pretty low, so the minor losses become significant if you try and increase flow rate significantly - which is what you need to cool 5 units on one loop.
For now, the shipping on the second individual kit for now is only about $15, so you get the entire kit delivered for about $65.
They were charging me 35$ to ship to Canada.