OK, for posterity then, since there may already be more info on this thread than anywhere else on the web, here's what I know at this point (if anyone notices anything different, I'm all ears)
Since Gritzner was a manufacturer and the decal appears to be one of the two styles they used, I haven't tried further identification.
Type of drive (Transverse(TS), Vibrating Shuttle(VS), etc) -
TS
Type and location of tension -
type I'm unsure of, but location is on the faceplate
Slide type -
Singer model 13 style, or were you meaning horizonal (ts) vs vertical (vs)?
Type, shape and location of bobbin winder - type being the type of bobbin it winds or otherwise?
I've seen two for this machine, the german link I posted shows a gear driven one, the ad from Needlebar shows it's a bobbin tire. Of course that makes me all the more curious. 
Importers badge or badge style -
no importer's badge. Manufacturer badge. Interestingly, I've seen the badge with and without web behind the spider but it doesn't seem at this point to help determine the age.
Finial style on top of needlebar and presser foot - I
'm not sure of the choices at this point as to the finial style. It's what I think of as "crown and sceptre" but I think that probably makes no sense to anyone but me. 
The foot looks the same as both my Winselmann and the F&R - what I think of as the unhinged German straight stitch foot. It's more curved than the Singer ones.
Casting differences in bed -
the main one that stands out is the "shield" or "crest" shape in the middle of the bed rather than the ovals and other shapes I've been finding. The toes look to have more detail than the Winselmann equivalent I've seen photos of and then of course the curlicues and feathers on the rest of the bed.
Rear access panel shape -
boomerang 
technical term
Serial number -
currently illegible. I may never know.
I think I see a 6 possibly a 2 and a 1 on the left of the thumbscrew and possibly another number right beside the thumbscrew on the right, definietly a 3 and possibly another number beside that - a 1? I've seen several Gritzners online where the numbers are all over the place and some are very lightly stamped - like the 2 I think I see in this one, so I don't even know how many to look for and what's just a casting oops.
[ATTACH=CONFIG]507758[/ATTACH]
Originally Posted by
SteveH
I think I discounted the one on Needlebar as being the same because of the "ferris wheel" not the cogged wheel of the saxonia and the much different hand crank. Rookie mistake, eh?
Yeah, I saw that one on fleabay. I wish you had to take a test before you could "improve" on an antique. Of course, I might fail that test too.
. The ad is also wrong because Gritzner didn't form until 1872 according to:
http://www.sewmuse.co.uk/Gritzner.pdf Which calls into question the 1872 on the German site. lol! Back to the 1870s to 1890s estimate.
I can totally see how the cast base would be faster and less labor intensive. I guess back in 1880ish, my hubby would have been happy when I picked the "low end" choice.