I have a semi-auto wren 44 gold. I does save weight, space and money.
When you have to sort out problems with your turbine,
I think it is more convenient to have the full control of the starting sequence.
I might not think that way if the wren engines were not that easy to manually start.
About cool down, well, I shut off the engine after taxi back to the pit.
Then I cool it down. There is no difference to me...

Yann