@ Awsterink: like the Jabsco the pump is DC magnetic drive, and as such there is neither gear noise nor that typical 50/60 Hz "buzz" you get in mains AC powered gear. It is absolutely quiet. Another user mounted his Jabsco on a metal garage door and even on this acoustic platform he had to put his hand on it to check that it was running.
I expect that, just as the Jabsco, it will run a bit hot, to the extent that keeping your hand on it will be uncomfortable, I guess about 50ÂșC. However two users have mounted their Jabsco inside the PC case with no adverse effect on case temperature., and no heat is passed on to the coolant.
The thing weighs a reassuringly solid 0.6 kg (1.3 lb) by the way, and should be mounted with a 3 amp in-line fuse.
What can I say? It's the daddy. Pity about the price...

but perfection costs.