I'm having great success with this set up!
My DSL modem is Cat5 hard wired to my Apple TimeCapsule/WiFi.
To that Apple TimeCapsule/WiFi I have my Roamio and one Premiere Cat5 hard wired.
In another part of the house I have an AirPort Extreme/WiFi that wirelessly extends my network from my TimeCapsule. To that I have my TiVo Mini Cat5 hard wired.
In yet another part of the house I have another AirPort Extreme/WiFi, also wirelessly extending my network from my TimeCapsule. To that I have another TiVo Premiere Cat5 hard wired.
Everything streams, transfers, FF, Rew without hesitation.
Added bonus: seamless WiFi coverage in and around my home!