I actually implemented something like that and tested on my own engine once several years ago. It didn't really help much on my particular engine and I was never really happy with it. I got much better results by increasing the number of squirts as far as I could (4 alt on that engine), and by setting the lags on tps and map as close to 100 as I could. This was on a 4 cylinder with ITBs. I was finding that the table lookups when using SD lagged far enough behind actual conditions otherwise that nothing I did could fix it. Squirting another pulse just made things go excessivly rich after the initial lean spike.
That said, I achieved the best results by going to sequential fuel. Also, I have found the off idle stumble many can't get rid of is because of incorrect ignition timing in the area just above idle. Tuning that properly helped me immensely.
Finally, I have found that in the existing AE code, the AE shot doesn't really start until the mainloop iteration after the one that the initial TPSdot > threshold happens. In our MS3 accel pump code, I have solved that problem, and those who have tried it have noted that it is easier to tune, more responsive, and has less deviation of AFR compared to the normal algorithm.
We also want to eventually extend in-progress squirts to help response even further.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.