"Backtrack" changed in Roamios?

I've had my Roamio Basic for a few months now, but from the first day I immediately noticed a change in the amount of "backtrack" when resuming play from a fast-forward or rewind at the 3x speed. It's still 3x for the first of the three available fast speeds, no? In any event, the first fast speed on my old Series2 would backtrack a little bit when resuming play, just as the two faster speeds. But on my new Roamio, the first fast speed doesn't seem to backtrack at all, or very little. In fact, sometimes it seems like it's actually jumping forward a bit, but I could be wrong.... I remember reading how the developers of the first generation TiVo did excruciating testing to empirically determine the best overall backtrack amount to try compensating for overshoot when resuming play, and it was different for each of the three fast speeds, both forward & backward. I think the Roamio might have changed the two other faster speeds' backtracks, too, but I've quickly gotten used to them — no problem. But the absence or at least very little first speed backtrack is thwarting my timing of resuming play coming out of commercials umpteen times every day, and I'm not able to get used to it and compensate. Anyone else notice a change in the first fast speed's backtrack?