Theic
I will have to re look up the link for the statistic that 70% of midair collisions happen in and around airports. its probably about right as its in and around airports that there is the greatest proximity of aircraft of all types and with that the greatest chance of a collision.
From a CAA report
c) A study of over two hundred reports of mid-air collisions in the US and Canada showed that they can occur in all phases of flight and at all altitudes. However, nearly all mid-air collisions occur in daylight and in excellent visual meteorological conditions, mostly at lower altitudes where most VFR flying is carried out. Because of the concentration of aircraft close to aerodromes, most collisions occurred near aerodromes
With the HoneyBee effect of the OH join and the multiple unneeded 90 degree turns that join has to increase the risk.
I probably have around 3000 hours in various piston twins and approaching an airfield with an overhead join would always position myself for a circuit height join usually straight in or downwind and request that. i considered mixing a fast twin with Cessna 150s and with all the blind turns was a risk factor electing instead to give final distance reports and communicating with down wind or base aircraft as a safer procedure.
Sometimes the join would be refused and you had to go overhead with the usual dead side descent and multiple turns but I always considered the risk factor as being higher, The turns a waste of time and money and those turns being uncomfortable for PAX. A relic of a bygone era.
Again the OH should be at 2000 in the OH not 1900 1800 1700 or lower which is often the case with cloud base restrictions and again often with aircraft scud running the base of those clouds and should you question the advisability of having everyone approach the same point at exactly 2000 feet?

Pace