obd link MX+ and/or scangauge

Trolling through forums and websites I came across the scan gauge and equivalent products which seem fantastic in their monitoring of engine parameters. Then I found OBD link that will do the same but send the signal to my ipad (that I use for my maps and navigation). Sounds even better .. then I thought .. well how could I use Windbooster Idrive to control throttle and use the scangauge or OBD Link at the same time. There is a OBD splitter and some say that they do work if piggybacked .. but others are saying it wont due to the polling rate and the inability of the ECU to provide info quick enough. Anybody running to in series on their 4x4?