That seems to happen on the HR44-700 too on 4x, not so sure on 3x since I don't use that very often
No, it ain't just you, Mike. I, too, use 3x almost exclusively. 4x seems to sometimes skip large chunks- i.e., to me, seems erratic± even if I could stop it just where I want consistently, it's not a good choice for me right now.
Now on the HR24 is a different story which is so much better in handling Trickplay even on MRV recordings.