I have locking tuners on my Parker and I love them. I have some doubts that they will end all your tuning problems. They will stop any string slippage at the tuner and this is good. However there are other factors that come into play with tuning.

Humidity and heat can change the tuning on my guitar. The strings don't slip out of tune but the guitar does. If you are changing tunings frequently, you will probly notice 2 things. 1. You still have to fiddle with your tunning pegs. 2. You will get a lot better at tuning. (This could actually be a good skill to develop if you want to change tunings frequently. ) Locking pegs can help but they are not a be all do all, when it comes to tuning. I also have to ask....How good is your tuner?

Are you are familiar with "Bottle Neck Guitar"? Let me tell you a story that you might find interesting. Greg Allman (who was one of the best improvisational gitarists ever) injured one of his fingers and he had to stop playing guitar for a period of time. HE WENT CRAZY, untill his borther bought him a bottle of excedrin for the pain. Greg, being the guitar monster that he was, ended up using the empty bottle to play his guitar without inflaming his injury. He apparently enjoyed it so much, that he deeply embraced the technique and became one of the best bottle neck players in the world.

I am not suggesting an excedrin bottle will make you an overnight bottle neck mystro. But I watched the fingerpicking clip you sent and I can't help but think bottle neck might give you something deeper to explore, with out too much pain. Playing bottle neck, you don't need to change fingerings to change chords and you can really slide notes with serious power. It might work for your situation, but it might not.... it really depends on the extent of your injury and how much you use it. But if you are already using open tunnings and fingerpicking, it could be a way to get an early parole from guitar prison and get that ax singing once again.

May not be your cup of meed but... I would suggest you google Bottleneck Guitar, Greg Allman, Lowel George, Derec Trucks, or Ry Cooder. There are many others that escape me now, but have a look and see if it catches your fancy... If it does, think about getting a bottle neck. Most guitar stores will carry them. I am pretty sure GT has lessons about it as well.