coming from a place that has only 13 or 14 controlled, and probably over 100 uncontrolled airfields, an accurate o/h rejoin is reasonably common, and something that you need to be sure you can do well. in general most GA and RPT traffic handles it pretty well (like in taupo), microlights and other nordo traffic can be a hassle, but a few things that i've picked up:
if there's other traffic in the circuit, and the runway in use is known, then a direct descent on the non-traffic (deadside) to join downwind over the numbers, instead of doing a full o/h rejoin, is quite common. a straight in approach is frowned upon, but not illegal. a mid-runway downwind joining is not really the done thing unless it's really quiet (ie no-one else on the radio in circuit).
andyrr - if you're joining the o/h from the deadside, it's no different, circle overhead until you're happy with the layout, wind direction, circuit traffic, then and only then, descend. you're only losing or gaining 1/2 a turn if you join from there.