Can I use this with a solid stain for fence? or should I get a different model? I would assume Semi-transparent stain is fine. Thanks

Semi-transparent stain is no problem for the Flexio 2000. Solid color stain is almost as thick as latex paint and would benefit from some modification for better spraying - There are a few things you can do to paint/stain to ensure it sprays well. 1 - Stir the paint/stain with a mixer in a drill until its creamy smooth, about 1 min per gallon 2 - Strain the paint/stain before it goes into the sprayer 3 - Add a flow agent, like Floetrol or Paint Easy (this is not a thinner) for latex paint – Penetrol for oil based 4 - Or you can thin, even as little as 5% can make a big difference, water for water based materials and mineral spirit for oil based material.