The hardware specs of these are a little bit too lightweighted for me, like I said below, in itself the idea to put that functionality into a router is great.
It's definitely not a powerful machine, though, you're right. You can hardly fit anything on the internal flash, and you can only recover flash space by setting it all back to first boot state again, so setting up an external overlay is the first thing you have to do. I think I only have about 10MB of RAM free, too.
It sounds like the Raspberry Pi would actually suit you better than most of the alternatives.
All these projects seem to want to either move your desktop to it or make it a media center.
I just want it to be a SSH and webserver that can handle occasional spikes of usage, like for instance private music streaming. For that I now have a Dell with duo xeon processor, each with 2 cores, which is pure overkill, and it makes noise too.
I'm using a TL-MR3020 with OpenWRT as the basis of a telepresence robot I'm working on. It has a USB hub connecting it to a flash drive (mounted as a filesystem), camera, and a microcontroller for motor control etc. It works really well.
http://wiki.openwrt.org/toh/tp-link/tl-mr3020 http://wiki.openwrt.org/toh/tp-link/tl-wr703n