Most decent installers will monitor false alarms and subsequent root cause, this would then lead to product sourcing.
Most others just buy the cheapest...
As long as it's a good quality detector and there are no temperature fluctuations or draughts then a PIR would be OK, however for the difference I would use a DT.
They are usually OK as normal in a hallway, takes a little more movement usually but fine in most cases.
Have a look on Security Warehouse for texecom stuff.