In message , R D S writes
I'm about to overboard a floor in a flat above a shop, currently tatty
floorboards, going over the top of it with 18mm T&G chipboard panels.

Is there any/much benefit to putting something like this in between?

http://www.ebay.co.uk/itm/261226286963

It will end up with underlay and carpet so i'm wondering if there would
be any benefit.

Pass:-)

Our builders used 6mm ply stapled to the old 9" boarding. Underlay +
carpet. No noticeable noise although there is no audio equipment
installed (bedroom).

--
Tim Lamb