I'd never heard of any of those sites, I checked them out none made me want to sign up right now.
I clicked through on okcofounder here wanting and expecting to be able to sign up only to be disappointed.
Ideas are essentially worthless without effective implementation. This roughed out one page implementation was effective for me and I'm clearly not alone.
Cofounderslab.com has a background that scrolls horizontally as I down-arrow on it. Stop that! Otherwise, the listings seem good. Best of the bunch.
Techcofounder.com provides no geographical search at all, from what I can see. Of the 3 ads in my area, 1 is from 2011.
Collabafinder gives me a list of people, but it seems I have to sign in to find more.
I have to register for Founderdating before I can find out if I want to register.
The rental market is massive and real and worth a shit-ton of money. Handling the pain of repairs and stuff? it's not even been vaguely tapped! That's a fucking good idea that's going to be hard to sell but it's a domino thing. When one major rental agency starts using it they'll all start using it. 'Your flat doesn't have residee.ce? How lame!'
Finding a co-founder is a tiny market.
Your advice is well intentioned and dog-fooding and all that lovely bullshit nonsense and really, really terrible.