You say your trike configured trainer takes a bit of time to build up enough
speed to lift off the ground, one thing and I didn't see it mentioned above is that
your wing incidence in relation to the ground may be a bit on the negitive side
meaning the leading edge is attacking the air in a downward positon in relation to
the ground. Simple check is to put the plane on a table and measure the distance
up to the trailing and leading edges of the wing, if the leading edge distance is less
than the trailing edge that is where the problem exisits. You can correct this in one of
2 different ways, lower the nose gear leg or put a larger wheel in place so that the distance
between the two are equal or the leading edge is up to maybe 1/8" higher than trailing edge.
Also firewalling the throttle on take off is usually the cause for most aircraft to want to
drift to the left from torque, gradual throttling up with a very slight "pinch" of rudder is
the way to keep it straight.

Bill D.