V4’s body structure is mostly the same as V3,. but there are some differences in the feet angles.
most poses should at least apply, but they may not be perfect, or exactly the same as the pose applied to a V3 figure, and you may need to adjust some things.
There are plenty of Pose packs and animations for V4 / M4 figures. ...possibly more than for V3
Hope it helps
It does. As far as feet go, I think those can fairly well be adjusted (I find myself having to adjust feet all the time anyway because when footwear for a V4 figure is applied to a V4 model, the default position often looks odd). The thing about V3 sets, though, is that they’re often cheaper than V4 sets when they’re still available, and many of them are even available free, so if they can be made to work with V4 reasonably easily, that’s a definite plus.