I'm certainly not looking to add any more mowing clients, and the focus is definitely in tree work, I'm still tossing around the name options. To me, Lawn and tree seems to roll off my tongue easier, my wife thinks tree and lawn is better as tree is the focus going forward. Logo work is currently being done, so I need to get that sorted asap. I have gotten quite a bit of my tree work from or through my mowing clients, and one of them has several rentals and they use me for general handyman stuff so I want to keep them around, I just don't want to add any more mowing clients and not have time to do the much more enjoyable/satisfying/lucrative tree jobs.
IMO, I think you're right on with dropping the landscape and keeping the southsound to retain the name recognition.