Some suggested alternatives...
May I suggest upgrading to WH-DVR?
Benefits of the upgrade:
Lower overall price: WHDVR with 2 playback boxes is cheaper than 3 HDDVRs.
More space: Standard HD-DVR is 60hrs each vs. 430 Hrs per WH-DVR.
Bonus - Networking: Right now if you want to watch what you record you will need to sit in the room you recorded it at; vs WHDVR you can access your recordings from any room you have a box. I will grant however that you need to set up your recordings from the DVR.
As a second alternative, you may wish to also consider upgrading to SignatureHome + 1 additional playback box
(you'll increase your overall recording time to 860 combined hours and get faster Internet, plus some cool extras in the process.
Just an FYI!