Actually they DO look pretty good,however their design and limitations would probably not have been favourable in large open stretches of water like the Atlantic,ideally they could have been used to operate in smaller shallower areas like the Celtic/& Irish Sea or St George's Channel for example,or even to make sorties up and down the Thames?
To operate in open sea they would as you (Jankowski) said probably have needed to be transported to their zone and the same upon return.
They could also have made excellent reconnaissance subs? due to their VERY small size and weight.
An interesting little sub nonetheless
