I have four (maybe five?) of these pumps. Been using them for about four months. Only three are in my setup though. Since it came from china and I didn't know the quality I ordered some spares. Also thinking about making a small fountain for drinking water for the dogs in the yard, so one was intended for them..
Anyhow. I use one submerged in my HERMS, works flawlessly. Another one is just recirculating HLT-water, and the third one is pumping from the HLT to MLT. I have not had any troubles with these at all. The only thing (I just wanted to try and it was to much to ask for) was when I tried setting one up as whirpool-pump, it just couldnt cope. I tried daisy-chaining two of them (output of #1 went straight into input of #2) which gave me some more flow, but they are just to small to deal with the hop-matter. Eventually the one which was connected to the other one broke at its outlet due to weight, the outlet snapped off.
I've ran boiling water and boiling wort through them and they do their job, just don't ask to much of them, like in a whirpool setup, and they're dead cheap. IMO they're good bang for the buck. And all ports are 1/2" even if the description says 20-something mm. But the best thing is they are magnetically driven, which means you can put a choke-valve after them without burning the motor.