Pullovers, straight or bent arms, are a potential great exercise, worth the time and effort put into it. The full stretch being the key.
If a BB'er wanting complete TUT (Time Under Tension) with the straight arm version, without losing that tension on the lats, than stop short of that top position. Bring the bar/db/swing bar to about the 3/4 lever, or when you feel the affect on the lats reduced. At that point, lower the bar back down to the full stretch position. This allows more of a complete tension on those lats. Also should get an excellent pump.
Try for a faster pace when doing this version of straight arm pullovers. But never forget the all important full stretch. Have noticed some, who are new to this exercise, use a too wide of a grip on a bar. Which can cause undo stress on the shoulder joints. If using a bar, than try for a little less that shoulder grip. Actually, the closer the better, in which case might suggest using a DB or Swing Bell. A EZ bar seems to work well also.
Which ever you use (bar/db/swing bell) never completely lock the elbows, but allow a slight break/bend to them. Though this exercise is not a power movement and a lot of weight is not required, a 100lb + will not be out of the question when getting seriously into straight are pullovers.
I come in contact with a few older gentlemen (55-70+) who would like to improve their older age posture/slouch/bent over look. The suggestion of moderate weight pullovers (either straight arm. bent arm or both) along with shoulder shrugs (traps) has improved most very well.
As far as bent arm pullovers go: in my view (whatever) it can be a prime upper body mass builder. Art Jones build his pullover machine on this concept and had said the the pullover was the upper body squat, as far as getting results were concern. Doing the bent arm pullover with the added presses (pullover & press) even advances this superior exercise much, much more.
Good Luck.
Good Luck.