Ask any model aircraft flyer or ultralight pilot about the effects of turning downwind, and they'll all agree there is a significant issue.
My rule of thumb is that if the windspeed is more than 25% of your airspeed, turning downwind will have a noticeable effect on flightpath.
And doing wingovers from into wind to downwind catches everybody out the first time. anytime You are maneuvering vertically, energy with respect to the earth has to be considered.