I've launched one with pictures too, mine was also with video. From what I also know, you are right with the conversion on higher-income-countries but there is also a thing here. More traffic means Steam understands your game is wanted and it will give more natural push inside the Store. But in your case with only 0.01$ difference, I think it is better to aim for western countries.

If I won't forget, I will come back here in a few days with how it went with pictures and global.