I wouldn't consider HLS as a replacement for existing LSP users - more like an alternative to Vixen 2.x. It supports RGB, can easily renumber/reorder channels or channel groups, has support for all the major dongles/interfaces (E1.31, Enttec Pro/Open, Lynx, Serial, etc). It can import Vixen sequences and Joe indicated it wouldn't be an issue making an exporter as well. It interfaces very well with Nutcracker.
If you're just starting out or are an existing Vixen user, I think this has some features that are very nice so give it a try - it's free like Vixen and fixes get done within a day or so (currently anyway). The big problem with Vixen is the show scheduler - it's very inefficient and a resource hog so HLS (or Vixen with xLights) may be a good alternative.