I used a 10 x 7 to break in the motor. It is still mounted on the motor. Should I take that off and put a 10 x 6 on it for flying?
What would the differences be?

I assume it is on a 45 size engine which the 10-7 or 8 is fine for. If it's only a 40 the 10-7 was probably more than the engine wanted to see for breakin and the 10-6 would be fine.

What is the motor & what is the plane?

It's a Tower trainer with a .46 Ball Bearing ABC engine.
I allready switched it to a 3 bladed Evalution trainer prop. I have no need for speed at this point of the game.

The 3-blade will make it easier to land in your short strip too.

Some 46 engines seem to like 11x4, 11x5, 11x6. Some like even bigger. My brother's TT46PRO, on a Big Stik 40, likes 11x5 best for the way he flies it. Lots of people are happy with the way the APC 12.25X3.75 works on the engine but it didn't suit my brother's Plane/Engine/Style.

I'd bet the EPS prop will work great on about any trainer.

Prop choice really seems to be voodoo. What works on one engine/plane doesn't work on another. Two people with 'identical' plane/engine combo will run very different props.

Sometimes it seems you need a box with every size prop ever built so you can experiment to find out what works for you.

If you want good all around stick an APC 11-5 prop on the front. Will fly the plane with lots of pull but also act as a speed brake for landing when the engine is idleing.[8D]

I also have choosen the APC 11 X 5 prop for my OS Max 46 on my Kyosho Cap232. Before choosing that prop, I tried about 5 or 6 other props. But when I put the APC 11 X 5 on the plane the performance jump was very obvious. The vertical performance was enhanced immediately which is what I expected, but the top speed seemed unchanged from the 6 inch pitch props I had tried. And braking on the down line was great as well as wonderful speed control on landing. I absolutely love that prop. It transformed the plane from lame to great.