Installed myself- it was so long ago now but I think it took about 20 minutes, including time finding a soldering iron and solder.
Definantly a different feel when it is switched on or off. Can switch on when driving, but not off, although it was advised to only switch on or off when stopped.
I just always hated how long it takes to change gears, and as this increases line pressure it cuts some time out of the changes.
You can definantly feel the gearchanges are stiffer and far more i guess 'deliberate', in that it doesnt feel like a soft smush into the next gear. Most noticeable at lower revs, as I believe its tricking the computer into thinking you are doing higher revs with more throttle. Up high I dont think there is much or any difference.
Only one complaint, and I did contact the guy about it, is that at idle she still changes stiff. No real problem, just not the most comfortable feeling with the wife and mother inlaw asking 'So you actually wanted it to be like this?' when you forget to switch it off and you remember there is a little slack in the driveline.
Very happy when I tow the boat with it, as I can just imagine a standard change slowly engaging under additional tow load, again this is deliberate and almost instant, when it decides it wants to change.
Very happy with it, will be looking at another one if I ever own another slushbox.