This seems to be splattered across three groups!.
QRPkits made the SLT. I have one. Its very slow to setup and a bit annoying.
If you've been tough it a few times its easy to get the last known setting...
Its hard to know when your getting close as a little to either side and
the SWR is high.
The basic design was about the same coils and caps in powers of 2.
It also means for 7 coils and 7 caps 15 switches with 15th to select
which end the cap is at. 255 possible combinations.
Automation is good. Use latching relays and put the cpu to sleep when
done (Arduino can do that).