You sound like an BG salesman Tim
Whats a BG salesman? sorry for sounding thick.
Whenever I get asked for a good plumber I tell people to go here As if it goes wrong there is a complaints procedure.
http://www.iphe.co.uk/
The main problem as I see it with the Salamanders are when they fail in Guarantee (I sell Hundreds) they then have the ability to blame the Installation, In one case I had some one with a 50 Gal CWS and it was not full to the Mark so they said there was not enough stored water, The reason the pump failed was there seals are rubbish.
I prefer the QT80 By techflow Quieter, Not as good flow rate, but still good enough, and a genuine back up service from the manufacturer.
I sell both so I am not predudice same profit margins ECT.
I would put a link to where I sell them but do not want to look spammy.