SEO specialists - step in here please
 

I've pretty good stable Google traffic growth at www.Signbucks.com
I have moved to that domain from www.SignBucksDaily.com// (old interface is still available with some extra characters into url, like i provided)

Does it matter if some old www.SignBucksDaily.com// site links are still working?
We are redirecting main page, which gets all the link juice and paysite profiles like http://www.signbucksdaily.com/sites/...ld_goes_young/ (13k in total) (to get it working follow http://www.signbucksdaily.com/sites/...d_goes_young//

Is it better for Google to do complete redirect of the old site to the new one, or it can be how it is? It has been 6m+ since the domain change. The old site didn't have that kind of SE traffic growth

Just use 301 redirection sitewide. If every page is redirected to its new permanent location you'll be good to go. Another issue is about the backlinks: you should ask your top referrers to change the url to the new one.

google is fine with 301 redirects. Companies merge all the time. it will pass the link juice to the new url