Nice review, it's presented very well but IMHO, this present just half of the overall picture. The missing thing is the head pressure, which matter much more for everyone around here than flowrate. The reason for this is that it's generally accepted that when you increase flowrate, head pressure suffer and it's tricky to get both of them up with a design. The XSPC is the one which is close to the top in both areas.

At least, it's interesting to see the differences with the inlet on the side and this tell me that the stock top is the best if you want to use the side inlet. Myself, I have a DDC3.2 with the stock top because there is no much space where I installed the pump. I wondered for a long time if it's a good idea to get a aftermarket top with side inlet but Martin said it performed worse. Your review confirmed the fact.