The 508, isn't MPEG4 compliant nor requires a monthly DVR fee.
Someone at Dish likes you... and more of your money, as well.
On the down side, you'll now pay an additional monthly DVR fee.
NOTICE: Plug the 722 into a phone line or you'll more than likely be charged an additional monthly outlet fee.
Read the fine print via Dish Network regarding Service Fees:
Additional Outlet Programming Access Fee: a non-refundable additional outlet programming access fee of (in the case of a model ViP211, 411, ViP612 DVR tuner and tuner number one in a model ViP722 DVR, ViP622 DVR or ViP222 receiver) or $5 per month (in the case of all other tuners) will be charged to your account for each tuner activated beyond the first. (For the purpose of determining the amount of this fee and whether it applies to a particular tuner, tuner number one shall be deemed to be activated prior to tuner number two in a dual tuner receiver and model ViP211, 411, ViP612 DVR, ViP722 DVR, ViP622 DVR, and ViP222 tuners shall be deemed to be activated prior to all other tuners). One $5 per month additional outlet programming access fee will be waived on a monthly basis for each dual-tuner receiver (models 322, 522, 625, ViP222, ViP622 DVR, and ViP722 DVR) activated. This fee will be waived on a monthly basis for each such receiver that DISH Network confirms has been continuously connected to your same land-based phone line and/or (solely in the case of a model ViP622 DVR or ViP722 DVR) continuously connected to your same broadband home network resulting in the functionality of the applicable receiver’s Internet-based features. DISH Network’s confirmation process(es) shall be the sole method(s) utilized to determine if your additional outlet programming access fee(s) will be waived; DISH Network DVR Service Fee: a non-refundable $5.98 per month DISH Network DVR service fee will be charged to your account for each model 510, 522, 625, ViP612 DVR, ViP722 DVR, or ViP622 DVR receiver activated. This fee will be waived if you subscribe to either America’s “Everything” Pak; HD Enabling Fee: A $7.00 per month HD enabling fee will be charged to your account if any model 411, ViP211, ViP222, ViP612 DVR, ViP722 DVR, or ViP622 DVR receiver is activated. This fee will be waived on a monthly basis if you subscribe to dishHD Essential, dishHD Ultimate, DishLATINO Max HD Essential, DishLATINO Max HD Ultimate, dishHD or DishHD Package (only available for residents of Alaska and Hawaii). A $10.00 change of service fee for each adult programming change and a $5.00 change of service fee for any other programming change will be charged to your DISH Network account. Hawaii Upgrade Fee: A non-refundable $4.99 per month Hawaii Upgrade fee will be charged to your account if you receive DISH Network service in Hawaii.