I openly admit that I'm a spec fanboy however this is due to my experiences of the customer service more than the bikes, its the very same reason why I will I will not buy specific Italian brands.
If your looking at the bike on spec alone I would agree with you. However if you are viewing the bike on ride quality and guarantee and support I think the Specialized Roubaix wins hands down
Halfords have a varied reputation with regards to the quality of bike building and servicing, let alone support. The nicknames this company has suggests it is not a one off experience.
By contrast the Specialized Concept Stores and Dealers have support from the manufacturer and extensive knowledge of the products. The Specialized frames have a lifetime guarantee and the boardmans do not.
The real question is are you willing to pay for knowledge, experience and support from dedicated cycle experts or do you want a bargain from the bloke who also sells air fresheners for cars?
I don't actually recommend everything Specialized make especially the Venge for everyone as its a really harsh bike, I really love it, its fast but very harsh and unforgiving. I have at times if you look at my post history also advised other brands and suggested people to buy Boardman

You state that Specialized are taking the wee, well I feel the same about company's only willing to offer a 2 year guarantee on their frames.
With advanced manufacturing techniques available these days, decent inspection process there is no reason why a frame should not last a minimum of 5 years.. Why not offer this, Why not stand behind your product.
I also find it strange that people compare specs but not service and guarantee's