That Alpa TC sure looks beautiful!
Just some thoughts...
I'm not entirely sure what the point of it over an SWC might be if you're looking for a hand-held, ultra-wide camera that you're not going to be using as a technical camera with lens shifts and tilts available. To achieve the native FoV of a Hasselblad SWC with 6x6 film with the CFVII 50c back, you need a lens close to 22mm focal length with extremely low distortion and high resolution. This is what I was looking for and despairing of finding until Hasselblad announced the availability of the XCD 21mm lens for X mount ... I nearly bought the X1D for that specific configuration alone.
The subsequent announcement of the 907x/CFVII 50c kit was more appealing since I could apply use of the back with my 500 series Hasselblad cameras as well. I ordered it with the 21mm lens, the control grip, and the viewfinder. Assembled in this configuration, it is a wonderful eye-level camera and matches the quality of what I used to do with the SWC. (I sold my '78 SWC to help fund the 907x kit purchase, sniff!) It has become my 'holy grail' of an all digital SWC, particularly with the addition in fw 1.3.0 of a distance readout on the LCD so you can accurately set the focus by distance with X system lenses.
While this has worked brilliantly as an "all digital SWC", as Jürgen pointed out the CFVII 50c has an excellent, versatile LCD to use as viewfinder as well. When shooting with the SWC, I would often work fast and loose, framing at waist level by feel. And the OVF support and viewfinder enlarges the size of the camera by a good bit, coupled with the control grip. That's what motivated me to consider making my own grip, hung off the left side, with the grip angled for best use at waist/low level eye point. (Photos are posted in the 'Fun with Hasselblad 907x' thread. This configuration both completely fulfills and expands upon my notion of the "all digital SWC" by netting a much more precise ability to frame and focus accurately even at low angles where I can't otherwise get my eye to a viewfinder. Add the 45mm lens as well, and now I have an excellent, two lens SWC+500CM+80mm kit ... which was always my standard kit in Hasselblad terms for the vast majority of my use.
While I think the Alpa TC is beautiful, from a practical standpoint the 907x+21mm+custom grip and/or control grip+OVF is at least a match in functionality and performance for hand-held work IMO ... and it's less expensive, and less expensive still if you do only want a 28 to 50mm FoV on the sensor format. The primary justification for the Alpa TC, then, descends to being the advantage of having other lenses/bodies/etc for use in a full technical camera outfit where the TC becomes the "light and handy, hand-held" adjunct. I see merit in that approach to this gear, but not enough merit in buying an Alpa TC kit solely for hand-held use in the absence of the rest of the technical camera ecosystem.
Eh. Whatever floats your boat is fine by me, I'm sure not objecting to someone preferring the Alpa TC over other kits, but the above is a good bit of why I haven't really considered it myself, offered in the notion of sharing points of view only.
G