Howdy-
Per most of the trimming charts floating around:

Straight and level, chop throttle, nose drops = need more down thrust
This is because you have too much up thrust, the plane is being pulled "up" under power, and you have probably compensated with too much "down" trim in the elevator. Remove the "up" pull by chopping the power, the "down" trim takes over and pushes the nose down.

Straight and level, chop throttle, nose climbs = need more up thrust. For the opposite reasons stated above.

I would go with what the plane indicates straight and level when determining up/down thrust, not inverted or on a 45d line. From that it does sound like too much down thrust.

I can tell you that my H9 Cap/DA100 has no thrust issues and the CG is about in the middle of the range, so I would be surprised if your thrust is too much off, assuming FW and standoffs are square. I have run the CG to the fwd limit in the past and still not experienced any adverse behavior. Assuming your CG is in the fwd part of the range, I would check thrust first.

I think you will really like this combo once you get it set up!

Bob