No its not un-reliable, they are built to handle the excessive power and torque, not only that but im getting way better millage now since the engine hardly works pulling a load.
Vadim the dynos we use for trucks are different then you normal dynojet, they are a static pull down dynos that load the engine up. We had 3 dodge pick ups with cummins diesels blow up because they couldnt take the load of the dyno, the way they do it is make you hold peak HP for 5 secs if you cant do it then it dont count. (unlike the FL dynos lol) If i put my truck on a dynojet i wouldnt be able to build more than 15lbs of boost as the torque would spin those rollers with ease.