We have the Shurflo Extreme that is variable speed and does not use an accumulator tank. I don't know anything about the Chinese products you refer to.
While I am sure that there is a lot of profit going into someone's pocket with the Shurflo (they cost a lot), it appears to be a high-quality piece of gear
. It weighs a ton, and all that weight is in the motor
windings, which leads me to believe they were engineered and built well. It is also dead quiet, which is better than the pump it replaced. That is due to the design of it.
pumps we have had in the past were similar, although much louder because they were not a variable speed design and the accumulator tank would hammer.
We did have one pump fail after a couple of years and Shurflo replaced it immediately by simply telling me to take their email
into any store that sold their pumps and ask for another free (we were out of the country when it failed). I don't know what the warranty situation is with the Chinese pumps you reference.