While not related to Sturmgeschütze specifically, I find the information below both useful and hard to come by.
Luchs Production and Issue
Thomas Jentz's "Luchs" title (No.22 in the Museum Ordnance Specials Series), lists the production and how the Luchs were issued.
On pg.5 he says of the Luchs production:
"...By 1 July 1942 the assembly contract had been extended to an order of 800, with delivery to begin in August 1942. The first 100 were to be completed as "Luchs 2cm". Plans had been made to convert to installing the 5cm Kw.K L/60 with the 101st vehicle as the "Luchs 5cm", with delivery starting in April 1943. By early February 1943, the decision had been made to discontinue production after completion of the first 100 Luchs."
So...only 100 Luchs were assembled, all of them by M.A.N. and all 2 cm versions.
Jentz lists the following units as having them issued:
* 2.Panzer-Späh-Kompanie/Pz.Afkl.Abt.9. of 9.Pz.Div. who got a full company allocation of 29 vehicles on May 27 1943, assigned as follows: 1 for Kompanie C.O., and 7 Luchs' in the 4 platoons (28) operating in the East. By 26 Sept. this unit had been disbanded and by Oct. 1 all the Luchs' had returned to Germany for rebuild, due to defective triple steering radius units which had plagued them. This disbanded Luchs Kompanie was re-raised only a week later and moved back to the west as 1.Kompanie/Pz.Afkl.Abt.9 of 9.Pz.Div. and begun to be issued 25 refurbished and newly assembled Luchs' piecemeal, between 30.Sept.'43 and 11 March '44. They were now organized into 4 platoons of 6 vehicles with 1 for the Kompanie C.O. Though they somehow appear to acquire another one by July 1 '44 as they oddly list combat strength at 26 not 25 on this date just prior to their employment against the Normandy Bridgehead in July/August'44.
* 2.Kompanie/Pz.Afkl.Abt.4. of 4.Pz.Div. also got full a company strength issue of 29 on Feb. 5 1943 and from other sources appear to operate only in Russia. They received 5 replacements which arrived on March 7 '44, followed by 3 on Sept. 3, 3 on Sept. 10, and 6 on Oct. 7.
* 4.Kavallerie-Brigade. had 5 (with only 1 operational as at Dec.30 1944).
* "HG" Div. with 1 Luchs.
* 3 were reported as being in the training and replacement units on March 1 1945
There is obviously a fair bit of overlap due to the rebuilt vehicles muddying the numbers so they sadly cannot just be totted up to 100, but a lot of spurious units are now eliminated, especially any rumors of the SS Pz.Afkl.Abt. using them.
For good sources of pictures, get hold of both of Concord's 4.Pz.Div. books or the Polish Militaria titles on 4.Pz. and the one specifically on the Luchs, as well as Ground Power No.21.