Dynamic read-speed setting

Would it be possible to dynamically set the read speed depending on the type of reads that are to be done? For example when doing long reads (reading a "large" number of blocks) pump the read speed up to full drive capability. When doing things that have short R/W cycles like writing a bunch of small files, reduce the read speed to the write speed or close to the write speed. Maybe even a step in the middle too. I know that the current 1.5:1 read:write ratio is a sort of compromise between read speed and spindle spinup/spindown time, but I am curious as to the feasibility of doing this. --John