Honestly, no I don't have shares in Heat Beads - but if people continue switching to them at this rate I may have to consider...
Dave, Heat Beads are just a premium quality briquette that burn in a very controllable way over a long period of time. These are designed for use in Kettle BBQs and for low and slow cooking. Weber do an equivalent in their Premium Briquettes. The main thing with Heat Beads and Weber Premium is that they burn with almost no smell or taste, unlike the cheap briquettes, so you end up with much cleaner tasting meat that tastes of the smoke from the wood you add and not the filler in the briquettes.
My advice would be to put your Tesco briquettes back in the shed and get them out next time you want to grill some sausages and burgers. This is what they are designed for. Initially you may think the cost of the Heat Beads is very high but because they last so much longer they do not work out any more expensive than the cheap briquettes and you dont get any nasty flavours from them.
Here is a thread I posted a year or so ago that compares the Heat Beads to brand of coconut briquettes that an importer was considering bring into the UK. It does demonstrate how efficient they are though
I only use Head Beads now and I add either pellets or wood chunks on top for flavour.
I hope this helps