Their claim:

"Giant Rider is capable of punching out 1.5G acceleration while the competition can only deliver 0.5G acceleration! "

That "punching out" was certainly carefully chosen. For a very brief period (fraction of a second?) they could jerk the whole cabin to give you the feeling of actual acceleration for that brief time, but absolutely not the feeling of sustained acceleration unless they are suspending the cabins and whirling them up to speed like amusement park swings.