The limiting factor for landing gear height (aside from scale considerations) is structural stability. The longer a gear is, the more torque it puts on the mounting blocks for a given force applied at the wheel. In one extreme case, I had a plane that would alternately tuck its mains and looked like a jet propelled penguin trying to run down the runway. Good for laughs, but not for flying.

You takeoff and landing charactersitics shouldn't change, since the tail will come up quickly on a takeoff run anyway. Once that happens, the plane doesn't know how long the gear legs are... if they are solidly mounted

This has been my experience so far on about 6 - 8 retract-equipped planes.