I bought this set about 3 years ago, I use it constantly and I must say that it is great. I love the slim design of the blades and it saved me so many times. I work as marine electrical engineer and I would strongly recommend insulated Wiha tools to everyone that works in that field.
I've been using these as part of my electrical troubleshooting. The slim profile of the bits is great for tall terminals with narrow openings, many of which I couldn't reach with standard insulated screwdrivers.
The only hiccup was that the locking mechanism for the bits has trouble engaging at first. Using a twisting motion while pulling hard (at first) will get it to engage, and eventually it will be smoother.