10 exp 7 or 8, who cares?
yes, of course the universe is only 14 B yr old at most. Your basic M class star is definitely the place to be. On the other hadn, if we ever acjieve interstellar flight, lat A and F stars will be great places for introducing advanced terrestrial plants and plancton for terraforming. We could jump start these abodes. So what if they only had another 10 exp 7 or 8 years left to go before evolving off the main sequence?