The front spring rates have changed a few times over the years. The 2016 set up was with SSL springs.
The 2005 set up was with Eibach.
Peter Mulberry has all the rates in his head.

The 2016 suspension is very well resolved. So much so that I've kept the standard Spax and not even thought about changing them yet.

The rears have changed from six leaves in 2005 to four leaves now. The change was around 2012, which was when the weak leaf spring period occurred.

I can only comment on the cars I've had!

On my Plus 4 there's about 5mm compression on the rebounds. It doesn't bother me as 5mm is a tiny amount. Had there been more thread on the base of the kingpin I'd have added spacers under the plate to eliminate it, but there isn't really enough thread.

2005 Corsa Red Roadster S1
2016 Saffron Yellow (Narrow) AR Plus 4