My head is 24" too

(23.5" maybe)
I use a PASGT no problems lol... I guess any helmet with those strap retentions are easily adjustable... But I doubt you can put rails and stuff on it...
Otherwise if you have time, just go to Toronto since you're around Barrie area... You could probably visit Huang's and test his helmets, or go to TAC 11, they probably might have helmets...
Maybe because my PASGT is a replica/plastic, my main complaint is how I hear a kind of echo/muffled sound when I talk hehe...