I got mine today. They are causing intermittent obstacle alerts causing flight to be interrupted. It seems to happen during forward motion. I have tried to refit them a few times and I had one propeller that was clipping the protector despite adjusting it a few times. I am not sure what is going on there. Here are a few images that you can see them.
That was the issue I was having with the front guards. I now only use the rear guards. I like the added visibility the rear guards provide, mine are painted green. I have not noticed any change in flight characteristic.
I just received my Tozo propeller guards today (from Amazon from a seller in China), threw them on my Phantom 4 (front and back) and ran a simple Litchi mission up and down my street. The first time I ran the mission it flew flawlessly then the 2nd & 3rd time I ran the mission it went up vertically and proceeded slowly forward and then stopped after a bit mid air and started rising higher and higher but very slowly. I could not get it to move forward or backwards. I even tried lowering it but it would not and it continued to rise higher. So I switched to S and was able to regain control landing it safely. I wonder if the guards had anything to do with it. I'll try the mission tomorrow w/o the guards to see if that was the problem. On another note after these incidences/flights and @ 35% I got a "critically low voltage warning" on a brand new, first time/flight, freshly charged battery. I wonder if the two events are related? I did turnoff the drone and controller, then back on, flew it hovering off the ground for a bit, landed it, and the error disappeared.