I was VLC for several months and every time I experimented with IF I ended up with huge adrenaline reactions and hypoglycemia. Sufficed to say I gave up on it as "Not for me". Recently I drastically increased my carb intake, mostly from fruit. My appetite has all but disappeared and I've been missing meals regularly with no problem.
Am I right in assuming that having some liver glycogen allows the IF process to work better? Is there some other mechanism that makes IF work better with a more moderate carb diet?
If your metabolism is now in good shape, your carb intake can be from zero to pretty high and IF should still work just fine. In this scenario, good metabolism means the ability to comfortably shift between burning ingested carbs and burning released/circulating fat.
It doesn't make any difference for me any more and my carbs vary quite a bit from day to day.
Note: Don't underestimate the influence of any qualms you feel about IF. That can be a self-fulfilling prophecy. If/when you want to, just eat a nice large meal and don't eat again until you are good and hungry. If you're tense about it, it won't work this time either.
It depends what you mean by IF. If you're just talking about surviving all of 16 hours without eating something then yes, filling your glycogen stores makes a difference because you won't need to switch to burning fat at all.