New, very sharp rippers like Clover Brand are the ones to use for 'between the seam' ripping. It's very easy to push too hard on duller seam rippers and that's what can stretch fabric or cause you to cut the seam instead of the threads.
I use both methods carefully, depending in how new and sharp the seam ripper is; and I only use the Clover brand which I replace several times a year. I buy their little brown handled ones; they are less than $5 and I consider them like my cutting blades....change often.
Jan in VA