Is your thrust line in line with the wing and stab CL? If so, down thrust probably isn't needed. If these lines differ, then it might be good to have some.

2 or 3 deg of right thrust is standard on most planes I like to fly (3D profile, pattern) and I trim the CG just as you describe.

After doing that, I like to use down thrust ONLY if I believe uplines are being skewed by thrust. To test that I first climb at various speeds and observe canopy or belly pulling and then compare with power off dive tests. The dive test should give perfectly neutral but climb test may differ and that would dictate how much down thrust. Some like to trim down thrust for level flight at a given speed, but I like to look at the uplines because they are easier to see (plane far away, line is always vertical, vs coming and going it's hard to judge perfectly horizontal unless you're VERY low).

Then I fly KE and see how it behaves. Normally, I just like to mix out any coupling there with the rudder/elev mix.