Watto,
I would always use a QS for a property- positive geared or not. But only while I pay tax.
A QS can find deductions you are to entitled to. (they probably won't find every deduction- they will miss out on some things).
My last qs was for a property which was built in September 1987. Building depreciation is $3,311 pa for a number of years ($825 for the last fy bcause it was only acquired in April). Depreciation of plant is $4,575 for the 2002 fy, $5,515 for 2003, and then going down.
This property is slightly positively geared (before tax).
The QS left out some important items- but even then, on the top tax rate, my tax has been reduced by $2.5K this year, $4.4K next year. Not big bickies- but WELL worth the report (cost was about $1K I think, for three lettable properties on a single block in Canberra- purchase price $277,750).
So I'd certainbly recommend it be done. Newer properties have more to depreciate- but older properties too can have quite a lot.