Kev, I bought my first electric jigsaw when they first were available, either in late 1946 or early 1947. Back then all were barrel grip. Visibility of the line we wanted to cut was not a problem because every one of my pals using jigsaws held them under the work. In those days my day job was constructing scenery for Broadway shows, so cutting complicated shapes from thin plywood was my cash cow.
Honestly I do not remember when I saw a 'D' handle jig saw for the first time, but it could have been in the mid 1960s. By then I must have replaced my first jigsaw a few times because that kind of tool simply was not as well made as they are today. At a store I tried one of those 'D' handle jigsaws, but rejected it.
I already owned at least 2 barrel grip jigsaws which were functional, and I did not intend to replace them, when my Festool dealer asked me to try a Trion PS300. By then I had bought about 12 Festools in the previous year and was making good money using them. Although I did not exactly need the Trion, I had the cash and I really liked the way it fit my hand. I think that was early 2007. Long story short, I am still using that same PS300.
I have not built any scenery since 1952 and in my style of cabinet making I hardly use a jigsaw daily. Personally I have no reason this late in my life to bother to learn a different way of using a jigsaw, so when the Carvex reaches the USA, I expect to buy the mains-powered barrel grip. BTW, long ago I also learned how to use a barrel grip jigsaw on top of the work when necessary.