The application is a general-purpose laboratory power supply and should have an output as clean as possible - within the limits of medium-complexity circuits and widely available components. Since there is no specific application / type of load to be regulated, I cannot say for sure that the ripple will be a problem however there may be times when it will.
I certainly don't mind the minimum output voltage to be 1.25V and I believe there are other modification which would allow the LM317 to drop as low as 0V, but let's discard that for now.
The circuit was tested with an 2n6804, but I still don't like having an additional component that will dissipate a lot of power and heat - it seems wasteful if it were alternatively possible to just adjust the LM317.
I certainly don't mind the minimum output voltage to be 1.25V and I believe there are other modification which would allow the LM317 to drop as low as 0V, but let's discard that for now.
The circuit was tested with an 2n6804, but I still don't like having an additional component that will dissipate a lot of power and heat - it seems wasteful if it were alternatively possible to just adjust the LM317.