Vue 11.5 does focus primarily on work-flow enhancements. While there is some nice stuf (I love the ability to merge partial renders into the final render and the improvements in material handling), it is not worth upgrading to the .5 version unless you are on maintenance in which case it is free.

Apart of that, I don't think that you can purchase an upgrade from 11 to 11.5? I would wait until 12 comes out and then strongly consider to get maintenance. Over the past 5 years, I have just paid ~$200 per year and had always the latest version of Vue. A very good deal in my book. I think the new renewal price is ~$260 and even that I consider a good deal for always having the latest upgrade of my favorite software.

Ciao

TD