I remember when the HR34 was introduced, people were going crazy trying to get one. There were almost hourly updates on availability.
Then the HR44 is announced, and the HR34 becomes a "POS."
The two units run the same software, have the same number of tuners and storage capacity. The major difference is that the HR44 has an outboard power supply and a smaller form factor. I can see little evidence that one model is more or less reliable than the other when running the same software release. While the HR44 is somewhat faster, I would hardly call the HR34 "slow" (it is comparable to our HR24s and H25s).
As to why only one Genie is allowed per account, I suspect it is more an issue with the current state of RVU client software (both the DirecTV clients and RVU capable TVs) than anything else.