OK gave it some more thought. Reason I originally thought of the beagle direction, is that almost the whole concept of the beagles is their IO, and that is what seems to be your user case, you want to control IO. Now the beagle concept is old, it started up before the RPi came along ...
What the beagles do well, is their focus on capes, that is hardware that adds onto the original SBC. There are alot ...
So first direction look at the pocket beagle(
https://beagleboard.org/pocket) its add on boards are click boards (
https://github.com/beagleboard/pocketbeagle/wiki/Click-boards%E2%84%A2), alas a quick browse of there click boards and it is mainly sensors, and you want relays and things. So the pocket doesn't seem to work.
Then the beagle bone direction, and turns out their is a wireless version - didn't realise one had come out (
https://beagleboard.org/black-wireless) I have the original Beagle Bone Black. Whats good about the design is the two rows of 46 headers, it means that boards that connect plug in on both sides - and that makes it stable. Also many boards that plug in you can add yet more boards to the top to stack. This works with many of the interfaces (e.g. you can have several I2C devices on the same bus, as long as they have different addresses ...)
Anyway check the beagle capes (
https://beagleboard.org/capes) and (
https://elinux.org/Beagleboard:BeagleBone_Capes) and you can get relay boards and the like - there will be some hardware there that fits your needs.
Then there is the question of the IP cam, are these connected wirelessly or via ethernet? Also how do you communicate with the device, wireless or ethernet. Anyway if therenet direction, it sounds like you need a hub/switch - e.g. you have enough ethernet connections, you can't find a board with enough ethernet sockets - so hub/switch needed. Alas that can't be a beagle cape I think (should probably check), the beagle interfaces are the slow kind, I2C, SPI, UART, CAN etc but ethernet needs fast - and I don't recall any fast beagle interfaces (other than the ethernet ...)
Now going wireless direction, you need to set up the SBC as a hub, that gives out addresses, and does blue tooth etc. I've never done that, so can't say how hard it is. But probably a good idea to check the WiFi/blue tooth is in the main kernel (e.g. the TBS problem its a legacy driver in staging ...)
Price wise, well this is looking more at the holistic direction, so there is more hardware than just the TBS. but the SBC part is at least comparable (BBB Wireless is about £60, and BBB (without wifi, with ethernet) ~£40).
Have to say, I am biased though. I have two beagles myself (Black and Pocket), and a panderboard. I like the design - think its well put together. So do see what others here have to say.
And the old cortex A8 is far slower than your A17 design ....
And a tad worrying, many of the old capes seem no longer available, which is a pity ...
Oh and just read you may want to add a HDD - thats harder, most SBC only do sd cards. If going HDD direct almost easier to start with a NAS ....