For anyone that's interested I came across this tumblog that's listing expired blogspots with pagerank which can be registered and used to build back links to your site. I have no need for them but maybe you do http://expiredblogspots.tumblr.com/
Yes, links will be beneficial if the blogspot subdomain has a decent amount of quality backlinks, page authority and page rank and preferably if you load unique & relevant content to place your link in.