Hakkapeliitta R does not have any spikes on them. That compound is even softer than the ones used in winter tires that have spikes like hakkapeliitta 4,5,7 etc. So if you remove the spikes from winter tires those might hold the summer heat in one place. SPiked winter tires need little bit harder compound so the spikes wont fall off and twist into bad position under acceleration and braking.
Hakkapeliitta
R tires will melt under the car quite fast if you drive them on the motorway +120 km/h at +25 celsius temperatures. By melting I mean the same thing that happens as does the regular tires on the track they gather some rubber chunks at the edges of the tires and wear off very fast.
Braking distances on studded winter tires on dry tarmac is over 10 meters and with studdless winter tires over 15 meters longer. Warmer the weather or it rains bigger the difference. Best summer tires stop 100km/h(62mph)-0 under 36 meters. Its quite hard crash if you need to stop at 36 meters with winter tires on...
Wider tires (175-225 range give also better rolling resistance than the narrow tires, but the rolling resistance force might be smaller in narrower tires + they have better aerodynamics.
I suggest everyone would read these pages first if they want to know more about rolling resistance:
Barry's Tire Tech
Barry's Tire Tech