Hey guys,
The so17xa, according to the drawing, is just a bit shorter than the NX05 and it's diameter is similar to the NX05 if your were to remove the lip flange that skirts around the the front end of the NX05.
I just made another cool revisit using the so17xa in a L1 head. I'll upload the pics later and post a new thread.
Regarding pics of the 27 mm VS the 30 mm optic, I leave that to sombody else.