Quite right - the overhead join is appropriate for non-radio aerodromes and the IP join is OK for aerodromes with people flying in a 'predictable' manner and with full RT. A low level join where you look UP at other traffic above the horizon before flying a climbing break when clear is even better in such environments. This will, however, mean that you couldn't have more than about 4 or 5 aircraft in the visual circuit at once. I regrettably conclude that, with the wide cross-section of skills displayed by the civil GA fraternity, the IP join is not generally appropriate.
But neither are those halfway-to-Heathrow cross-country navigation exercises flown by many pilots at White Waltham, for example.......