The JLR dealer in Grand Rapids, where we bought our Disco Sport, works on older Rovers-they had a LR4 in the shop getting a new engine while we were there.
As for the software update-that also goes along with a new relay for the compressor. If it's actually working, yah you'll want to get that update but it's not a right this second kind of deal. If you go from Hitachi style to AMK style or back the compressor won't work at all, and will throw a code on you. Had that happen when I replaced a POS Arnott on one of my former LR3's. I found that my present Chinese Hitachi style compressor would share parts with an old Hitachi I swapped out of a RR and between the 2 of them I got one working compressor.

 

Chinese Hitachi I thought they were made in Japan.
No I'll be looking to put exactly what's in there now what ever that is..will find out tomorrow,as what's in there now has lasted 17 years and over 200 miles.
Just don't want to have update software

 

dealership service

 

My local LR dealership will not look at anything older than 10 years

 

Maybe I should clarify.
Somewhere in the past, my LR3 had a Chinese copy of a Hitachi style compressor installed. That compressor builds good pressure but wouldn't exhaust due to a mashed O-ring in the valve.
I also had on hand an old genuine Hitachi unit from a RR L322 that had good control parts but wouldn't build any meaningful pressure, like 60psi max after running until the thermal cutoff kicked in. Between the Japanese Hitachi and the Chinese knockoff I put one together.
If you look om Amazon you'll see the cheap ones offered in AMK and Hitachi style, I was surprised at just how close the copy of the Hitachi was.

So that would be why it dinna work

One is Hitachi, one is a copy, everything except the screws looked to interchange

 

Genuine Hitachi is made in Japan but there are lots of knock offs around including the Dunlop compressor.