Usually, cloth seats last longer than leather. They are warmer in the winter and cooler in the summer and much less slippery. The padding is the same for leather or cloth.
Heated seats are an option for all Volvo seats, and most northern cars have them.
Trading seats is very simple to do. Just unbolt them from the floor, unhook the electrics, and slide them forward 1/2 inch and lift. Be careful about the SIPS, don't let the seats fall to the ground :)

Leather seats tend to wear on the upper bolsters, from the seat belt, and the driver's left leg. They do need to be treated with Lexoil at least in the spring and late summer, to keep them from drying out and getting hard. Never use a vinyl protectant in leather.

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)