I have a Media Server at home (Ubuntu) running xbmc to three TVs in different rooms and 3 Streamzap USB Receivers at the top of each TV.
The USB Receivers are automatically recognized:
And you can point any IR remote you want to it, grab the code sent by the remote and associate that to any keyboard key, mouse or even script. In this case, I customized the IR-keymap for each receiver so it adapts to each of the 3 IR remotes.
[ 7256.462641] usb 2-1.3: new low-speed USB device number 4 using ehci_hcd
[ 7256.610651] IR NEC protocol handler initialized
[ 7256.613752] IR RC5(x) protocol handler initialized
[ 7256.618028] IR RC6 protocol handler initialized
[ 7256.621283] IR JVC protocol handler initialized
[ 7256.624695] IR Sony protocol handler initialized
[ 7256.628036] IR MCE Keyboard/mouse protocol handler initialized
[ 7256.631921] lirc_dev: IR Remote Control driver registered, major 249
[ 7256.632876] IR LIRC bridge handler initialized
[ 7256.638174] Registered IR keymap rc-streamzap
[ 7256.638396] input: Streamzap PC Remote Infrared Receiver (0e9c:0000) as /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3/2-1.3:1.0/rc/rc0/input15
[ 7256.638627] rc0: Streamzap PC Remote Infrared Receiver (0e9c:0000) as /devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3/2-1.3:1.0/rc/rc0
[ 7256.638881] input: MCE IR Keyboard/Mouse (streamzap) as /devices/virtual/input/input16
[ 7256.639289] rc rc0: lirc_dev: driver ir-lirc-codec (streamzap) registered at minor = 0
[ 7256.639344] streamzap 2-1.3:1.0: Registered Streamzap, Inc. Streamzap Remote Control on usb2:4
[ 7256.642637] IR RC5 (streamzap) protocol handler initialized
[ 7256.642948] usbcore: registered new interface driver streamzap
In parallel, I have one of this (http://www.usbuirt.com/overview.htm) with which I conducted successful experiments some months ago using Ubuntu 12.04. My idea was the same as yours.
Lirc and irsend worked perfectly. I tried some bash scripts using irrecord and irsend to control all A/V devices and even other electronics, everything went fine.
I gave it up because it was not really portable. I wanted something portable to control at least the TVs/xbmc. When I plugged it to my desktop the IR signal wouldn't reach other rooms. And when I plugged it to my notebooks, well, it was just ugly. So now I use the official xbmc remote in my android phone.
EDIT: By the way, do you remember handheld/PDAs, like Palm and HP iPAQ? Many of them had embedded IR receivers/transmitters, had touchscreen and IR configurable remote control software. Many people used them to control IR devices. You can get one of these PDAs almost for free nowadays.