I had ridden bikes from my late teens to early 30's. Started riding again after a gap of more than 20 years. The power difference in middleweight from my younger days to now is staggering. My old SRX 600 made 42bhp, my more modern Triumph 600 made around 95bhp. There are significant differences, even allowing for the very different engine configurations.

I'm thinking about a new bike again, lightweights like Husqvarna 401 or KTM 390, make 40 bhp and weigh 140 kg. Plenty fast enough, easy to manoeuvre on road and move around your garage.