By now you know that there's more to Chile than the Bio. Drive 80 kms to the Rio Queuco confluence, the lower of several possible take-outs for the Bio. Some float the Bio from the Rio Lonquimay junction to the Queuco.
Drawbacks are a long shuttle and kilometers of flatwater.
In favor is the luxury of a multi-day trip. I prefer to run the two canyons as separate one-days, utilizing the hotsprings between the canyons for camping. The upper section includes the Lost Yak and Lava South rapids. The famous Rio Malla waterfall plummets into the river just above Lost Yak. To run this stretch drive up from the hot springs, cross the volcanically silted Rio Malla on a wooden bridge, and continue until the road comes back to river level.