Can you share the dimensions and weight of the RC400? It certainly looks a lot bigger than the TC in that photo, but it could be the lens mount deceiving things.
Cambo RC400:
Size: 120 x 145mm (W x H) excl. handgrips and tripod mount
Weight: 500 grams (excl. lens, excl.handgrip, excl. tripod mount)
Movement: +/- 20mm (total of 40mm)
Tilt: built-in to most lenses. Rodenstock: Rodenstock: 28mm+, Schneider: 43mm+.
Alpa STC (from Alpa.ch):
Size: 140 x 146 mm (body only)
Weight: 580 grams (body only)
Movement: +/- 18mm (total of 36mm)
Tilt: available with separate adapter + SB lenses. Rodenstock: 32mm+, Schneider: 60mm+.
Arca Factum
Size: 135 x 140 mm (body only)
Weight: 640 grams ("factum" body + Variofinder + Adapter + TripodMount)
Movement: +/- 15mm (total of 30mm)
Tilt: built-in to body. Available on every lens.
So on spec the Cambo is 20mm less wide, basically the same height, and 80 grams less than the Alpa while offering 2mm more movement in each direction (4mm more of total movement).
But as we all know spec sheets only ever tell part of the story. Both systems have optional handles, measure their weights without the adapter plate, have different lens mounts and viewfinders that have different weights, sizes, and layouts. Moreover Cambo's lens panel can contain a Tilt-Shift mechanism where Alpa uses a separate TS adapter in between the lens and body.
But clearly both cameras are in the same league: light, compact tech cameras of high quality with one direction of movement and compatibility with the lens panels of their respective bigger brothers.
Likely the weight/size of the two is close enough in practice (with back/adapter/lens/accessories mounted) that prospective clients will choose based on other factors like ergonomics of the grip, balance in the hand, ease of using the shift, range of movement, initial cost, cost of accessories/lenses, and the other bodies in their respective systems (since there is a great deal of intra-system compatibility).
If size/weight is important you'd want to get the size/weight of the system with all the bits that you personally plan on using. We'd be happy to arrange that for anyone looking at a Cambo.