I saw an earlier post about being able to purchase VZ Branded (or Retail) Equipment as the cost of renting the boxes scales very high after a couple of years.
One of the benefits of only offering VZ Equipment is that VZ gets to have more control over how the information is presented to the user (think of Apples model with many of their devices). I certainly understand wanting to offer the most amount of options by using only VZ Equipment however the point of escalating costs is very valid.
How about an option to trade in your older equipment after 2 years (similar to VZ Wireless). Many customers are offered 1 or 2 years contracts to lock into FIOS Service. Hard Drive sizes increase in new boxes and that is a common complaint from what I have found that there is limited storage space. Most of the other limitations of the DVRs appear to be resolved with IMG 1.9 coming later. How about after 2 years you can get the newest, fanciest Motorola/Cisco new larger hard drive, faster innards, etc.? Call Customer Service and then send you a new one, you toss the old one in the same box and send it back.
It would be more hassle and inventory to control but you would also be phasing out older stuff and able to EOL it from VZ Supported Products and giving the FIOS crowd the newer stuff. VZ already offers this to cell customers.
Guessing that 2 years is sufficient time for notable product enhancements in the equipment.
Alternate suggestion - if there is no trade up program, then discount the rent rates for equipment that has been in house for 2 years. As it stands, customers with older product are currently paying the same fees as those with new fancy boxes that have better internals. That does seem like a discrepancy.