Hopper/Joey are completely different animals (no pun intended) and during installation, especially with multiple receivers, any of them are bound to throw hissy fits at any point. Once they are set up and past installation, very reliable, but before hand, high probability of having to deal with 1303s, 015s, 833s, etc. . When I installed my third Hopper, I did everything EXACTLY right, yet, it still tried to screw me with the 015, until I read on SatGuys about resetting to factory defaults. Then the other Hopper decided it didn't want to detect the right switch, only detected 1 sat, until I did a red button reboot. I was about ready to pull my hair out, but in the end it worked and still works great.
So not only do you have to know all about how to wire things up, but Dish also tells the installers about how to get around all the installation/software-related flukes. Things aren't always as easy as they seem... Personally I think that their policy to come out for leased receivers is fine. After all, you're only paying anywhere between $0-$200 (in most cases) for 1-2 $450 pieces of equipment and 1-6 additional $150 pieces of equipment. The least you can do is let them properly install it. Now, if you buy your own receivers, that's a different matter.