Hi WaynesWorld
Welcome to the forum! I would have to say that Beersmith would benefit any brewer. Extract or All Grain. Seeing how you are already moving to Partial mashes, it will be of more benefit, in that you can customize a recipe to what you like. If you like Hoppy or Malty beer, it will tell you what your expected IBU, or bitterness ratio will be. Then you can dial in recipe into what your tastes are. You can see what different Malts will do for you when you add them to your extract. It gives you information about the type of beer style you are brewing so you can see if it fits the style. It is a virtual database of everything that makes beer: Malts,Yeasts, Adjuncts, Hops and Misc and there is a large following so you are sure to get help if need.
If you have questions or even answers for that matter. Join in on the fun!
Cheers
Preston