I tried it with a zotac ion atom 230 system, 2gb ram. It's theoretically plenty powerful. It ended up running opensuse as my home workstation instead with it's nice built in nvidia graphics and DVI out and a little more RAM. This was about 30-50 days ago. I put a ocz ssd in it for workstation use.
With RouterOS, I could not get the current version of netinstall at the time to be able to install routerOS on a USB stick. I tried the 4.5b-something version and it wouldn't properly install 3.30 or 4.5. I was hoping for something efficient where I could just move the USB stick to another computer for testing. It would apparently install, but not boot, unless it was a bad install? I was using an Aspire-1 netbook with XP to do the netinstall.
I ended up putting in this with a small inexpensive hard drive instead:
Amd am3/am2+ motherboard with nvidia chipset
http://www.newegg.com/Product/Product.a ... 6819103681
http://www.newegg.com/Product/Product.a ... 6817151085
It was similar money to the Atom system, but several times faster. It uses 50w of electricity idling and 70w under load, which I consider reasonable. A little more electricity than the Atom, but the company is paying for it where it's installed.