The Carneddau is going to be considerablly tougher tham Moelwyn!!!!
Moelwyn comes in at 8.5mile and 2500ft and you did it in 1:51. Carneddau weighs in at 9mile 4200ft.

To put it in perspective Richard Roberts (extremely expirienced and fit Eryri Harrier/welsh int) runs Moelwyn in 1:18 then Carneddau in 1:40+ so a runner of his calibre can add on 20mins on for Carneddau.

You need to be prepared to be out there for at least 2:15 - 2-20(ish). And if the fog is down are you able to Nav your way around???
It's one of the toughest races in the calender.
Hopefully I'll be there :-)