I've been using the TextBlade for two weeks.
I have not made any changes to the default mapping. I have made almost exclusive use of the TextBlade during this time on iOS and Macs. I do have to make occasional use of a Windows based machine to which is attached a "regular" 101-key board. I can't make use of the TextBlade on that computer.
I've been surprised to find that the learning curve for the TextBlade is not nearly as onerous as I had anticipated. The main adjustment necessary is learning not to over-reach. I still do that when going for the B and ' keys. Fortunately, the over-reach for the B lands on the wedge, but enough of my finger is on the key, so the B is almost always (99%) registered. I am still adjusting to the ' as the movement of the right pinkie to the right is no longer required. Interestingly, I've adapted to nearly all uses of the ' except for "I'm" and "I've" these being my most error prone contractions and the miskeys almost always happen when I'm in a chat session (Messages or Skype (aka Lync for Mac for a little longer).
For normal typing, I am at my prior typing speed in sheer CPM measurements though the error rate is a little higher than I like (see above). My fingers find most of the green shift characters I need with little thought thanks to the well thought-out positioning of these characters. I find that I am consistently using the Edit/Select functions on the TextBlade and it is a joy to be able to edit from the home row.
I do have problems with numerals on my right hand, I consistently shift all my right hand numbers to the left by one position which I attribute to bad habits developed over the years because of some physical problems with my right hand. I'm slowly correcting this, but this ultimately might the worst problem I fight for some time to come.
There is a magic geometry between you, your hands, and the TextBlade. It took me a bit of experimentation to find it, but when I dialed this in, it was obvious. I tend to slip out of this positioning when I'm tired, but again finding the geometry is not difficult once you know what to "feel" for.
To me the feel of the TextBlade is excellent. I find that when I'm typing along, the feel really does actively help me to get into a rhythm that helps me to type longer, with less effort and frustration than using a normal 101-key. The reach for the keys is so much less, the tilt of the type-blades makes a definite difference in the comfort of the arms, wrists, and hands.