Hello guys...I know I am many years too late to reply BUT I am one of the owners who have upgraded the latest firmware...and YES it does have significant improvement in fuel economy!
Before: City 9.5L/100kms and up to 8.9L/100kms
After: City 8.7L/100kms and up to 7.8L/100kms.
Mainly I felt that the charging of the Hybrid battery and the ECO mode have became more sensitive and thus engages more often.
Furthermore I also noticed that the IMA does ASSIST more and longer.
But one fault still remains...it is that the Hybrid battery capacity tends to be low and ASSIST doesn't last long at all. Wished upgrade battery is available in the future that increase the capacity...or even Lithium ion can help a lot!
It is shame that Full Hybrids like Fusion Hybrid (which I own as well) and/or Toyota Prius which can run on motor alone (which drains the battery and demands much more juice) lasts MUCH LONGER duration than a mild hybrid battery like the Accord Hybrid.
Don't really know why!