I calculated the stem angle to be around +16 degrees based on this image but perhaps someone who has used any shape of math the last decade could verify this.
+16 degrees is right. Pretty huge difference in horizontal reach as well compared to a conventional -6 degree stem.
90mm = 13mm less reach, 32mm more rise
100mm = 14mm less reach, 35.4mm more rise
110mm = 16mm less reach, 39mm more rise
120mm = 17mm less reach, 42.5mm more rise