A great set of 1944 - 1945 WNF factory pics has just been found by Peter, over on LEMB. Among them is this great sight of a Bf 109 G-10 being engine tested in deep snow, Winter 1944 - 1945...
http://www.flickr.com/photos/2809206...in/photostream
As for the others, taken between April and August 1944, I'm still looking for the W.Nr's of Bf 109 G-6 "PN+IY",
http://www.flickr.com/photos/2809206...57632867434203
Bf109 G-6 "DU+SL"
http://www.flickr.com/photos/2809206...57632867434203
Bf 109 G-6 "PR+QS"
http://www.flickr.com/photos/2809206...57632867434203
Fantastic that those images are still extent... and thanks for your help!
Cheers
Marc