I'm going to be replacing all my backpack sprayers. I currently run the solo sprayers. I'm thinking I'm going to get 1 for cool season apps, 1 for warm season apps, 1 for insecticides and fungicides, and 1 for roundup with the mowing crew. My solo's are ok, but parts are pricey. My fert dealer carries some SP sytems and the ones he has in stock right now are the commercial YT189. Anyone used these? What other backpacks for spot treating and small back yards do you like?