The power shuttles used in true construction equipment, like a front-end loader is really the best of both worlds, but its a really confusing world of shuttles. The older John Deere 310 Back hoes, had a power shuttle on the steering column, but a stick shift on the floor to select gear, and that really could only be selected at a dead stop. However, yiu could throw from F to R freely, even when in motion. Lull/Grad-All forklifts, had shuttle on column, with a rotating knob to scroll through 1-3 or 1-5 or however many gears, and could be scrolled though at will, while in motion, as well as F to R while in slow-motion. Then yiu have 'hydralic reversers', sycro shuttle, non-syncro, partially syncro, ect; and the manufacturers don't see to really explain on the website what Their shuttle really is.
Add to that, the stuff we did on construction equipment, very well might not be ideal for the long life of the machine... I'm sure it's 'best' to come to a stop or near stop, before F to R.
Edit: also, a 12 or 24x24 speed shuttle, is generally only shiftable within a given range; or in some cases not at all between gears (other then F/R), others can, and I believe some can shift gears within a range, but only with a clutch