Well, the '+' has always been a little confusing cause it's somewhat unlike other open source software, but you guested it ... it means within the series - *possibly* the .0 of the next hop up (the 2.8.x you are running). Did you try the 'extra stuff' to install? Again, maintainer's link on that page. Encourage you to inquire so they know someone is interesting in using with 2.8.x. Others might as well.
'spirit of sharing', Ken