Does open canopy creates drag?
 

I'm not sure but it felt like it.
Any other reason to close it?
Talking hurri and spits.

There seems to be no penalty for open canopy
No increased drag
No wind noise
No problem at max altitude

The benefits are

Improved visability
Easier to jump out

Thanks.

Don't be stupid : close that canopy. It's a sim not a FPS : it needs immersion and fair-play to be enjoyable.