Just got some 45-105 GHS Bass Boomers (identical to the Flea signature set) back on my 424, and very happy the bass is to see them again after a month with Swing Bass. I suspect that's partially because the Rotosounds were too responsive to the infelicities of my amateur touch, but in general the tone of the instrument seems a lot more even across the fretboard with the GHSs. In the UK, Bass Boomers are usually alarmingly priced, but Bass Direct have them for a much more reasonable £22+postage. To they're worth it because their straightforward character seems to match the 424 so well.
Whilst sorting the action the tech has left the pickup heights as the previous owner had them, which means with both pickups it sounds fantastic but the neck soloed sounds a bit underwhelming. Bridge soloed with tone turned right down can have its moments too.
After a few days with only the TRBX noodle neck for company, the BBx24 tree trunk seems much more comfortable. Given that my hands are definitely just medium-medium, I don't really understand why I find this to be the case. Best guess: my thumb is more relaxed as it doesn't have to press forward to grip the back of the neck. In Fenderspeak, would the x24 neck be called a U-shape?