I fitted the Librands door checks to my 2009 4/4 Sport in 2010. It was the first "upgrade" job on the car I did. I found it easy enough and am very happy with the doors kept properly open since then.
As said before: make sure to protect the door/wing after removing the leather straps.
I refrained from drilling the existing holes. I found that with a few washers placed under the fittings I could reuse the original screws with no problem.
Also my Morgan has a left and right side not being identical to the millimeter. The most time I took during installation was to get both door checks aligned to the degree of perfectness my German genes needed to be satisfied ...
Also with my checks the chrome dome nuts did come loose once or twice. I added washers here as well and since then: no problem.