I use Gabbers for all my robos (with the exception of 2 of them who live in a Perfecto glass tank)...all 23 of them!
They seem to love Gabbers...I think they like the shelf to hide underneath and then to run along the top. The little house that sits on top of the shelf is also a favourite...I think its a good viewpoint for watching what everyone else is up to. They tend to fill their pouches full of millet and then retire to the little house for some private munching.
I've seen that beautiful looking wooden German cage before and I'm struggling to remember what people thought. I think the concern was that with wood, it tends to soak up urine so after a while, it may get rather smelly no matter how hard you clean it. Also, you need to ensure that there's ensure space for plenty of wheels (ideally one wheel per hamster) which I suspect there may not be in that cage. It does look stunning though!