we have been using gridgroupingcontrol. it provides very powerful out of box functionalities(filter, sorting, column selection, grouping etc) and give a big room for customization as well. we achieved our desired goal by using it and saved a big chulk of development time. one thing i would like to mention is their support. their direct support has been very responsive and helpful, in average 1 day turn around time it has helped out a lot during our development and all most all the time the solution they suggested solved our problem as we expected.