I used the ACs the first time through, and found them hard to keep alive, so this time I didn't. But now when I summon them for the first time, an L12 Meleny gets an 83 HP jackal, and Rgr9/Rog3 sneak attacker gets a 53 HP jackal, and a Rgr6/Rog6 archer/picker gets a 51 HP jackal. ... So summoning at a later level does seem to affect starting stats for the AC. ... But I'm not sure why so little difference between the Rgr 6 Jackal and the Rgr 9 Jackal?