Check engine on test bench? Concerns???

Are there any disadvantages such as overloading or a check of the engine on the test bench to be feared? A patient who wanted to have his Harley tested on the test bench expressed corresponding doubts as to whether this is really so good! Reason given: am the days for a further training in South Tyrol and wants to visit the company Hirsch in St. Gallen via an East-West Alpine tour (Brixen, Merano, Chur) and have engine tested there on the 16th of July. And second question to the Swiss or other Alpine pass: Will either turn over the oven and then Flüelapass towards Chur or instead of Flüelapass over the Julierpass. Which one, Flüela or Julier. has more driving fun? Have fun and good ride on all sides! Kraxelwolf and Testwolf