I just checked whether I could print to an Epson CX5300 AiO connected to my Airport Extreme that is also serving as a Time Machine Air Disc, from my WiFi connected MacBook. I asked for a new printer to be added, the Epson was spotted immediately on Bonjour, there was a pause while the appropriate drivers were located, then it was added to the list of printers, including it's correct location as being attached to the Airport Extreme.
Time Machine is also apparently working OK via a non-powered USB hub to the external 2.5" HD that is my archive. I can retrieve files from it so have no reason to suppose the next backup won't work.
Ain't Apple wonderful!
I also had a look to see if Image Capture could connect to the Epson for scans. No such luck. It can see but not scan from a Canon MP750 AiO connected to an iMac 500 in the same room. I'm guessing a scanner has to be physically attached to the MacBook to work. It's not a problem as I would NOT relish a scanning session where I have to walk 20m there and back each time I wanted to turn to the next page for copying. It's easier to move the MacBook to the AiO or just use the iMac.