The first AS engined 109G-6/AS were produced from December 1943 and entered service with JG 1, JG 3, JG 5 and JG 11 the following months. DB 605ASB and ASC engines adopted most of the modifications made for the planned DB 605DB and DC (K-4) (mainly the larger supercharger of the DB 603 was bolted on the DB 605) and were later kept in production in parallel with DB and DC versions to increase production. These engines were all rated for 1800 PS. The 109G-6/AS had similar high-altitude performance in early 1944 as the 109K in late 1944, differing only in structural details (G-6 wings and tail unit, armament etc.). The streamlined engine cowling of the G-10/K-4 was adapted from the 109G-6/AS. In late summer 1944 they added MW50 injection for increased low altitude performance creating the DB 605ASM that powered the 109G-14/AS. G-14/AS and G-10 are practically the same aircraft differing only in minor details and red tape.
Beginning in December 1943, 686 G-6/AS aircraft were built or converted from existing airframes, along with 76 G-5/AS, 16 G-5/R2/AS, and 68 G-5/R6/AS. The number of DB 605AS and ASM engined G-5s, G-6s and G-14s during 1944 was approx. 2500 aircraft. In addition to these, DB 605D engined G-10s and K-4s entered service in late 1944.
Thousands of high-altitude AS engined 109s flew in 1944, almost exclusively on the western front. They were not "rare" by any definition of the word.
The AS 109s were tasked with protecting the bomber interceptors by engaging the Allied escorts. These were the Luftwaffe aircraft the Allied fighter pilots were actually
fighting with. These were the fighters that were
not ordered to just run away.
IMHO in all 1944 scenarios the Luftwaffe should be given 109K-4s to simulate 109G-6(14)/AS interceptor escorts.
Bf 109G-6/AS (W.Nr. 412 179) "black 14" belonging to Fw. Horst Petzschler of 2./JG 3, early spring 1944 (winter camo). Fw. Otto Büssow was killed in this aircraft in May 1944 while fighting P-51s.