You do get to transfer your three most powerful demons out of your OG compendium when you start Vengeance, so you get some carryover from having played the original. I get why they didn't allow direct save game transfers on account of features vanilla doesn't have that would need to be accounted for in Vengeance, such as Magatsu Rails, the landslide of new side quests, and the few dozen new demons available to recruit and fuse.

I get the irritation with the Golden Syndrome. If I'm not sure I want to double dip, or I am not confidant the game will do well enough for an upgrade, I'll wait.