For what its worth, when we moved into our house in 2018 we took the decision to take advantage of grants to install a Ground Source Heat Pump and Solar PV.
There are differences in terms of capital costs for sure, GSHP has much higher costs, but they operate at similar levels in terms of the heat they produce. We have no issues with heating our house, its relatively well sealed and insulated. We have underfloor heating everywhere and that is designed to use low temp water for heating anyway.
As
@TringSaint said, they produce low temperature water, so in terms of heating a house, you may find that you need to replace all the radiators to achieve similar heating effect.
Hot water for handwashing/bathing's is fine too, although the system needs to routinely heat the hot water cylinder to 70C (IIRC) to kill legionella, but that's managed by the heat pump.
My understanding is that heat pumps are entirely capable of producing hotter water, but the efficiency goes down dramatically.
As a consequence, it is likely that they will also need to change their hot water cylinder too, as the hot water generated is typically at a lower temp.
I haven't looked recently but as far as i can tell there is no economic argument for changing, the Cap Ex (even with a grant) is likley to take many years to recover (if it ever is).
The cost of running for our system is not dissimilar to the cost of gas we were paying previously, but i saw on a recent news story estimates of a few hundred quid a year. A quick google gives range of average costs of c.10-18k, taking into account the 7.5K one can get means a cost to the consumer of c.2.5-10.5k.
Edit: forgot to say that the Solar PV has paid for itself by now and some, but that's because we don't expert anything so the value of the generated power is worth more to us. Despite the predictions the GSHP will never fully pay for itself, although we will get back a significant chunk in payments. The rebates are calculated by the amount of energy the GSHP uses, clearly when the weather is warmer you dont use so much so you dont get paid as much, and the winters have been pretty warm in recent years.
IMHO if it isn't broke don't fix it, there will come a time when we have n o choice potentially,