Here a picture I found on a Dutch forum. The pic comes from the Premacon site. It shows both the 944 and 956. (the 944 is the demolition model). Gives you an idea about the size comparison.
From what I read on the German forums, the 944 has had plenty of upgrades and fixes so it is a very reliable machine. In the 2 build threads I read on the first kits from the 956, there have been some teething problems, but all in all seems like a solid machine. From what you can tell from the pictures, the detailing is excellent. (better than my Komatsu, but there is the price difference)
Should you be interested in those build threads - lots of pictures in them. (one is Dutch and the other German):
Dutch:
liebherr r956 premacon (this is where the above picture comes from)
German:
Liebherr R956 - Bausatz von Premacon
Here 2 pictures I took from my Fumotec Komatsu to give you an idea of size. Sadly enough I do not know how it compares to the 944 or 956.
Regards - Stephan