I have a Cuisinart kettle for boiling water, then I fill the Buono directly off of the boil. I can then vary temperature depending on if the Buono is cooled by water from the tap, or just at room temperature, or adding a small amount of the boiling water to heat up the kettle. I then pour into the Buono from the Cuisinart kettle and can quickly hit most any temperature with a subsequent delay of time for cooldown if necessary.
I also have Bonavita which is very convenient, but I have modified the Buono with a plug for a smaller stream of water.
Oddly, the Bonavita temperature base is now acting bizarre that when turned on the led just starts counting vs. setting the temperature! Very odd, had to dig out my spare base because of this.
Anyway, they both do a great job.