We have 2 Hoppers and 4 Joeys and they are all as reliable as the ViP's. At first, like with all brand new DVR systems--like the Genie hiccups--can be quite buggy. However, Dish has really made the Hopper/Joeys quite reliable. For a while, it seemed the living room Hopper was rock solid while the 2nd room Hopper seemed to reboot a few more times, but now they both seem at the same high reliability.
I enthusiastically recommend the Hopper/Joeys for anyone. We haven't regretted our upgrade in the least. It has all been a vastly enhanced experience. I would say it would be no worse than the current ViP experience. Just be certain to contact Dish if you are not satisfied and let them replace any units until it all works as advertised. As good as the Genie and other DVR solutions may be, the Hopper really is the best out there today.