For the sake of clarity, "upstream" is by most definitions "before" the mechanical pump.
Anything before the mechanical pump is "upstream" and therefore on the suction side. Given the recent threads by DanH and others looking at the incredibly small internal passages of these devices, any suction side mounting should be considered a really bad idea.
Yes, there are thousands flying with them on the suction side - that does not change the fact that its a bad idea. After all, there are still people in this day and age that take up smoking cigarettes too. Just because people do something does not make it smart.