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.
I must confess that I don't understand the connection between whether the property is positive and getting a QS report.
I see ips as a business and to run the business the most effectively a QS report allows me through our current taxation system to improve my cash flow position on a month by month basis It also provides useful data to assist in insurance calculations. This would be equally true whether a property was negative neatral or positive.
You will find that the cost of report is heavily outweighed by the deductions allowed.
You may however want to speak to an accountant regarding the capital gains implication of depreciating the building and how this fits with your plans for the ip(s).