No reason to wonder. The money is in the 50p, £1 and £2 coins, but in terms of effort expended does not represent a huge return given any sale will likely be through ebay with its fees and then posted with the Royal Mail.. If the three are selling more individually than the sets are as a whole, then breaking them up is a no-brainer as a dealer, but less clear cut on eBay with the relevant fees and costs taken into consideration. I can sell £1 coins at any time for now - I think I only have 1 or 2 left. But I still have a healthy selection of 1/2p to 20ps. These I could use for small change at any time should I need to. There are collectors of all denominations, but most do just the three mentioned.
As a rule, the question should be 'why do you not break them up?' Given the involvement of the general public as opposed to knowledgeable numismatists, I still think this feeding frenzy will end in tears.