ajohn

I agree with Paul. The bird looks too bulky and heavy-billed for a small acro, and you noted it seemed large in flight.
The plumage pattern seems perfectly normal for Oriental Reed, and the behaviour suggested from these photos (i.e. staying in the open long enough to photograph it several times) also supports that species.

ajohn

Black-browed seems to be more wetland-dependent than Oriental. Even in the Deep BAy area, Black-browed is rarely seen away from reedbeds or grasses close to water. Oriental is fairly regularly seen in bushes, trees, etc. even in relatively dry locations. This also relates to the fact that Oriental is also more 'showy' than the other reed warblers (as I mentioned before).

I would expect Black-browed to be harder to see away from the Deep Bay area than oriental. Even at sites like Long Valley, I don't remember seeing many Black-browed in the past.