I was shopping for cables at Hobbyking (as my local r/c shop bit the dust,) when I found this device for $2.91.
Turnigy SSV5 Analog Servo Travel Stretcher (180 Degree)
"The SSV5 analog servo travel stretcher is small and lightweight, it is the ideal solution to increase the travel of your servo to almost 180 degrees."
Sounded promising - but the reviews weren't too positive. So I got one along with various cables and rcvrs.
Here's my test results, using my existing r/c gear in EBT #12's tender plus a new analog servo. You can see the movement is 90 degrees (LH tx stick.)
Here's the results with the servo extender in the cable. Not much difference - I reckon about 30 degrees more movement.
Pretty much in line with the reviews. Shame really - it would have been useful.
(Next test - wifi rcvr. stay tuned. . .)