Would agree about the wheels being a factor on hills but I have two good bikes and I have interchanged the wheels. Both sets of wheels are within 50 grammes of each other and they have the same make and size of tyres and tubes. So I can intercahnge the wheels and should not feel a difference between the wheelsets and I don't. But one bike sails up hills and the other flies--no matter what wheels are fitted.

Boreas in ride trim is 16 1/2lbs and the TCR is 17 1/2. The TCR is CF and Boreas aluminium. Both bikes are stiff- in fact the TCR is too stiff with the wrong wheels fitted. But it is the TCR that flies up the hills.

But the OCR is 20 lbs in ride trim. It has climbed mountains successfully with lightweight wheels but it was harder than my current bikes. Not a fair test though due to different gearing and fit not being the same. Get the bike fitting perfectly and it will ride everywhere better.