it's interesting how you always find great reviews before you order something new, and once you do, it's all downhill from there... I guess I'm going to have to learn and decide for myself firsthand. tbf though, the review you're linking to is 4 years old
The tektro brake leavers that those are based on are pretty dismal tbh, fine for ~£18, but not anything more.
http://road.cc/content/review/56215-retroshift-levers