The simple answer is yes but you will more than likely need a back up.
Also do not have high demands when the ambient temps fall below zero. Just because the makers say they work down to minus 15 or 20 degs, the COP value will not give the savings (so Gas will still be cheaper) if the unit keeps iceing up it then costs power to melt the ice. The savings will be made when temps are above 4 degs this will give a higher COP value (on most units above 2.5) rising to above 5 at 17 degs.
For this reason I only use my ASHP above 4 degs C many daytime temps rise well above this temp when I replace my heat ( I do not loose much heat as I fitted 4″ Celotex on walls and floor) so make use of the higher COP values to give a faster pay back. My heat pump has saved my Gas bill 80% on the previous year, you may need the 20% for when its below 4 degs for long periods.
If operated in this efficient way a heat pump can transfer heat cheaper than Gas, i.e. for every 1 Kw consumed 3, 4. or 5 Kw output can provide big savings. N.B. I use mine in a Hybrid form with my Gas boiler which is off when above 4 degs C