Picture an un- strung "straight" limbed bow laying on a table, on it's side. A straight limb bow's limbs would be straight from tip to tip. A stringfollow's limb's would gradually arc backwards towards the shooter, and lastly a reflexed bow's limb's would arc away from the shooter.
Notice in the pics how the limb tips are just behind the riser when unstrung, hence the term stringfollow, as the limbs naturally "lay" towards the string, or belly, side of the bow.
Reflexed, or backset, limbs impart speed to a bow, normally this adds a bit of thump at the shot and decreases stability a bit.
Stringfollow, or deflexed, limbs are very very mild at the shot and are very stable shooters.
Straightlimb bows blend these 2 caracteristics, good speed and stability, with a mild thump at the shot.
Of course speed variations rely on how much backset or defex are put into the limbs.
I will gladly give up 3 fps for the forgiving mild nature of the stringfollow.