The sdQH will have the same size. That said, between the SDQ (even the H) and the XD1, there is an ocean of differences is favour of the XD1. Comparing them at an IQ level is plain silly (as well at feature level). We can compare the price and yes, this is the only advantage for the sd. What achieved hasselblad is just superb and it is a dream camera for landscape, true 16 bit colour depth, 50 well resolved MP, huge latitude and clean files from ISO 100 up to 6400 (even more than a D810) and MF presence even if small MF. 60 minutes of exposition without trigger, no shutter so no vibrations, video, weather resistant body AND lenses, superior batteries, clean UI and tactile screen, lighter than a SdQ, 1/2000 flash sinc... the list is long and yes, we can't compare those two cameras. OK, it come at a premium price but it is not that expensive in MF world.
For anyone wanting to go serious in photo production I can only recommend people to invest in the XD1 because it is a major tool for many years to come without any problems (no moving parts also). That + a modern APS-C (fuji or whatever) and your good for 10 years.
For anyone who want to continue to cope with strange raw developers, wasting time in mastering the un-masterable, fighting highlight issues and poor DR with grad filters and hours of pp for "ok" results, then yes, a sigma camera will do the job, but you will suffer.
So sometimes one can ask himself a question : "Should I invest in a real professional camera even if it's costly or should I stay in my sub par niche with my dreams, hopes and twisted forum specialists ? " Because SIGMA cameras are fun tools, for sure, but in no way really future proof your work.
The hassy is expensive but photography is expensive, very. If photography is you true passion and major source of income... the Hassy is the best tool (and can be paid in 2.5/3 years).
TIP: If you work as an author or as a professional with State councils or big associations or big industry you can ask them to pay the camera for you in exchange of you work on a certain period (or number of missions). Of course your work and skills should be up to the task. For me it will be this way for example. An organisation pay me the camera and lenses in exchange of 20 missions. It's a good deal for them and a good deal for my passion.
(EDIT: ) Hope nobody comes here with extrapolations from raw-therapy or whatever because this is not how it work in the real world when you should produce files in a given time and at a given quality. Anyone who experienced the "stress" of a commissioned shoot know you can't mess up manipulating files for hours because it is not that good at first...