governors in setcpu or other scaling apps basically sets how the cpu will scale to the max and mins that you set in setcpu. in interactivex the it will revup the cpu to the max and min much faster so that the uptime to the max setting is quicker then using conservative or pwersave. the last two will rev up to the max settings much slower and could cause lag but may save batter to some extent. smartass is very similar to onedemand but basically will have a screen off profile.
i have tried interactine x with the aggressive freedom kernel and was getting pretty good battery life. 12-16 hrs with moderate usage.