Just wanted to pop on and say we too went the reducing oz route, but moved the feed earlier in the evening too with each oz drop (we were still doing the DF at about 11months and dropped this way). I was worried personally about E still needing liquid of some sort and that's why I went that route rather than watering down. Also, we were getting waking in the am from wet nappies so the two together made up my mind.
You need to try what you are comfortable with though
If you find B is grumpy from a smaller feed, you could try moving it earlier so he is less hungry, but as it's not a DF it would involve waking him earlier which you might not want to do. It could be a bit like a modified W2S though if you think part of his wakefuless is habit, and this could help? (Thinking aloud, not sure if anyone has tried this before).
Another alternative is to go the watering down route and once you have watered down a bit, then try reducing the amount in total. So e.g say you get down to 7oz of water but 3oz worth of formula, the next step could be reducing the amount overall but keeping the 3oz worth of formula, so sort of a mixture of the two methods if that makes any sense.
