It's interesting to me that you're experiencing very good results with this method. I use an extended bolus for every meal as well as an immediate bolus. I deliver both of them at the same time, about 60 minutes in advance for breakfast and 30 minute pre-bolus for other meals. I found these prebolus timess work for me by watching my CGM.
Your method differs significantly from mine in that you don't deliver your carb bolus until much closer to meal-time. I'm going to try to approximate this with this morning's breakfast. I can't use the temp basal feature on my pump because it's limited to a +200% temp basal setting, in other words, it's limited to 3 times the underlying basal rate. Using your numbers, you ramp up your basal from 0.4 units/hour to 2 units/hour. That's a +400% temp basal, beyond the reach of my Animas PIng temp basal.
What I'm doing, instead, is setting an equivalent extended bolus which I direct to deliver x units of insulin over y units of time. I think delaying the carb-bolus till closer to mealtime will tend to lower the possibility of going low right before or after eating.
This is different from what I'm doing and I'm curious if it might enhance my post-meal trends. I've read Dana Lewis's 2014 piece on how the liver can soak up a lot of the initial glucose from a meal if it is signaled strongly enough by active insulin and it detects enough of a blood glucose differential between blood coming from the small intestine via the portal vein and the blood in general circulation.
I tried soon after I read this article with an "early pre-bolus." It was essentially a small, often less than one unit calculated as a correction dose to bring down a BG of say, 110 mg/dl, to 83 mg/dl. It seemed to have some effect but nothing dramatic for me. Looking at that effort in the light of your experience, I'm guessing that the active insulin levels were not high enough to trigger the liver into storing more of the immediate post-meal glucose and thus dampening the post meal rise.
Using my current carb bolus + extended bolus regimen with a sufficient pre-bolus time will often see my BGs spike up into the 160 range post-meal. Sometimes it only goes in the 130's. I'm curious to see how your method works for me. I'll try it for several days and see how it performs for me.