Yep, I thought this too, Alan. However after looking at www.marinepower.com
(europe) and www.mercurymarine.com
(usa/canada) its is clear that quicksilver make only inflatables and valiant make only ribs. Its quite possible that most of the tubes and fittings are shared though as they are both owned by Brunswick.
The quicksilver heavy duty does look a good boat and will certainly last. Have you looked at these though? Maybe a possibility if they are cheap. These are essentially the smaller Valiants rebadged for the US/Canadian markets.