My experience is only with L 360 Mk.II, which may be different from Legacy.  During Phase One I had two open canopy events due to bad overcenter adjustment.  First  shortly after takeoff, canopy popped about 120 kts, rose about 3 inches and very noisy.  I returned for landing, flying normally.  Second, near cruise speed, canopy rose 2-3 inches, very noisy.  I engaged autopilot, slowed to about 150, pulled canopy down with strap attached to rollover and re-latched it.  I see no way canopy can rise to open position, at any airspeed.  That would double or triple the flat plate area, would require hundreds of hp to overcome.  I wonder what CZ and other engineers think about this.

Anyway, it’s never a good thing unless you are bailing out, but I see no reason why it would cause loss of control. FLY THE AIRPLANE!  Ed Gray