Besides the single driver Aporia (which I haven't heard) I don't think Silbatone has made any speakers. So they don't 'employ' GIP drivers. I think GIP is a separate Japanese company who have just been invited to participate at these German shows. They brought two of their own speaker systems and placed them alongside the WE system.
I met JC Morrison at the Euro Triode Festival in 2010 and he gave an interesting talk about getting a good result from the D3a. I think the Silbatone pre-amp uses an LCR type equaliser with D3a's and a transformer volume control, but like the power amps, they deliberately won't make more than a handful of pieces.
The bass system had the two pairs of drivers facing each other into a 12" wide 6ft tall 'slot'. The drivers were open to the rear. I think this had been put together just prior to the show.
I get the impression that the venture is like a travelling museum to demonstrate the WE speakers. The owner, who I think was conducting the demonstration, did say that the WE15's were probably the third best speaker he had but that the better two would not have fitted through the doorway.