As far as Comcast is concerned, if you just use a plain DOCSIS 3.0 modem from the compatible list, »mydeviceinfo.comcast.net/, you can use any router you please. AT&T Uverse I do not know enough about to say yes or no.
Ditto to prev poster as far as Comcast, I used my Netgear n300 w/ them a couple of years ago w/ a Motorola sb6120 DOC 3 cable modem.
As far as Uverse, it'g going to depend on what Uverse service is avail to you, it's either VDSL/tv supported or IPdslam which is internet & voice only. With vdsl, yes you can migrate the Asus over, you just have to set it up that way, with IPdslam probably not the case as most are getting the Motorola NVG510, mayber others who might be using that equipment as you've inquired about can chime in.
I have VDSL w/ my n300 for all my LAN, hooked up behind the RG/3801, other connections to RG are for STB's for TV only, works fine.
You can use your router with the NVG510 also. Setting it up is somewhat of a pain but it's definitely possible. Find the instructions here: »www.ron-berman.com/2011/ ··· e-users/