I think those tools a nice, but usually I make them seamless in photoshop. Simply clone the original layer 4 times and move each one 50% out of the canvas, in all 4 directions. Then unify these 4 layers, then use the eraser tool to erase the obvious seam that is now in the middle of the layer.
additionally, and that's the hardest part, I am transplanting, brightening and darkening parts of the texture until it tiles without siginficant repetition. You should have a little blitz app that allows to quickly test a texture on a wide open plane (add a reload texture function!), so you see how it looks when there are 50 or so tiles onscreen. Things like grass or so will look repetive when you don't get rid off significant things.
additionally, and that's the hardest part, I am transplanting, brightening and darkening parts of the texture until it tiles without siginficant repetition. You should have a little blitz app that allows to quickly test a texture on a wide open plane (add a reload texture function!), so you see how it looks when there are 50 or so tiles onscreen. Things like grass or so will look repetive when you don't get rid off significant things.