I'm not quite sure how to explain this. It's like a whole cat report when we take into consideration how a cat is doing, we look at the spreadshee and get the 5 P's, is he Preening, Purring, Playing, Peeing & Pooing. If the 5 P's are in place we figure the cat is doing well.
It's the same with the ss, you need to take into consideration, the cycles before, is he bouncing from a low number? If so then 1.4u might be a great dose. But once the bounce has cleared 1.4u might be way too much insulin and 1 unit might be the right dose. It's like you have to stay one step ahead of his bg's.
So since he has been dropping all day I would back off the dose a little bit to try to find the next best dose for where he is headed now.
I hope this helps, if not ask more questions.