I originally had a CAA PPL back in the eighties then, after a longish break, came back to flying 7 years ago and decided to go for the NPPL due merely to the fact that it is easier and cheaper to maintain (not necessarily to obtain); certainly not for medical reasons.
I can honestly say that, as a fair weather bimbler, there has been no practical difference between the two.
I have never once wanted to do something and been prevented due to having an NPPL, in fact I've had more fun this time round.
The money saved on medicals can go towards the two-yearly instructor flight.
I honestly don't know why (unless they have ambitions beyond the PPL) everyone doesn't do it.