So that implies that 20% of people sharing their information are getting a SCOP of 3 or under, yes?
But you would need a SCOP of 3.5 - ish to 'break even' compared to mains gas, and almost 4 to beat heating oil on current running costs. Energy prices for gas and electricity will be going up by around 20% in April, due to EPG changes, but hopefully coming down again around Q3/Q4. In the meantime, my oil cost per litre has dropped from around 80p a litre to around 73p this morning, with no standing charges. So right now, a heat pump would be a very large up-front investment for significantly higher running costs and and an even larger timescale for, hopefully, eventual 'payback'. Sure, prices will change and who knows what things will look like in future.
For now, they may a viable option for many people, but they are certainly not the 'universal panacea' that some are making them out to be.