My Neko has a later onset - you could be seeing some of that in Marley. I found that a +3 is more useful for me as an indicator of how the cycle will go, but ECID.
The jury is still out on the Young Again carb %. The company has not done the lab analysis to get the As-Fed or Dry Matter Basis numbers which we need to show what the carb % numbers are for this food. No doubt it is low carb but we don't know the exact numbers. However, if you read Dr. Lisa's web page, in all cases, wet food is better than dry food for cats. If you have made the switch to wet food, I wouldn't go back to dry food. Cats traditionally aren't big water drinkers and an all dry food diet can cause other issues. Some people here have also seen that a few carbs (4-6%) is better than none or hardly any carbs (1-2%).