Because of the change in shift points ( slightly higher RPM ) on both up shifts and downshifting going up hills, fuel mileage will be reduced.
That being said if the manufacturer thought the trans wouldn't handle it , they wouldn't offer the program. The higher RPM moves the fluid , through the trans and cooler quicker ( better for the whole trans ) and the higher RPM keeps the torque converter cooler when the trans is in gears where the lock-up feature isn't available. Over all easier on the trans.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.