I'm sure there is always due diligence since the people pitching can always lie about purchase orders and the like. Sometimes a shark will even explicitly mention that the deal is contingent on something else coming through.
I've watched both and for some reason I find Shark Tank much better. I'm not sure if it's production or just that spark for reality TV that seems to be perfected in America. The personalities of the sharks probably has something to do with it, or the mix since both Robert and Kevin are also on Dragon's Den.
I've seen all three shows extensively and actually prefer the BBC show the most. IMHO, the BBC one is the most serious version and even though you have to get your head around some of the UK-specific stuff at first, you'll learn a lot from the show. Canada's Dragons Den and, even worse, Shark Tank, are more heavy on the drama and personalities, so there's more flash, but less substance.
Also, Peter Jones on BBC Dragon's Den strikes me as an incredibly intelligent investor.
I've watched both and for some reason I find Shark Tank much better. I'm not sure if it's production or just that spark for reality TV that seems to be perfected in America. The personalities of the sharks probably has something to do with it, or the mix since both Robert and Kevin are also on Dragon's Den.