Depends on your definition of high speed.
I define high speed as 100+ mph for sustained periods of ten minutes or more. Above 100 mph, any shield that is 4 inches wider and 2-4 inches taller than stock is going to have an increased effect on the bike.
Speaking strictly of closed-course conditions :winksmiley: ...
I've run the +4w, +2h and +4h, both with and without flip, at sustained speeds of 135 mph. I would not recommend that practice in a strong cross wind of greater than 25 knots. But head-on the shields performed well with no unexpected adverse effects. Nothing squirrely, nothing weird, but not something I recommend as a repeated behavior. Oh yeah, don't forget to take off your top box too.
If you are consistently running triples then stick to something shorter and with less drag. Otherwise you are giving up too much aerodynamically to the squid you just blew away. Ahemmm, sorry about that!
It's been my experience that the flip performs very well at highway speeds up to 70 mph as posted maximum on many American slabs. The flip serves to expand the quiet envelope without the need for another 2-3 inches of shield height. Effects from cross winds of 20-60 degrees off-trajectory path have minimal effect and no more than on any other shield of similar height and width, IMO.
Just my $.02