Ok, quick update now that I have been using the groundwounds for just over six weeks on my P bass:
When I fitted them I needed to make an adjustment to the truss rod, presumably because of the higher tension. I found that I can set the action much lower than with roundwounds. This is a significant benefit for me. I find the strings just as playable as roundwounds, unlike the flats I tried some years ago which required much more pressure from the fingers to fret cleanly.
The sound from my P bass, which has a Wilkinson pickup, is clean and punchy just how I like it, with virtually no string noise. After 6 weeks playing which includes 3 gigs, 5 rehearsals and daily practise the strings are still sounding good. After about 3 weeks I found the E string was a bit quieter than the others so raised the pickup slightly which sorted it.
There used to be an intermittent dead spot around the 7th fret on the D string which disappeared when I put the groundwounds on. Can't explain that. The sound/volume is now very consistent across all strings.
All in all I'm very happy with them.