Panasonic DFD

Whether you need to switch to Panasonic lenses would ultimately depend on your own use experience, of course, but from my experience, it is unlikely the case.

I have tested reasonably extensively the 45/1.8, which supposedly does not support DFD, and the 45-175, a slow zoom that focuses faster than the prime anyway on non-DFD bodies.

On the GX80, which is a current-gen Pana body with DFD, both focus blindingly fast. Even on AFC with tracking, I cannot say that I observe better behaviour from the zoom, unlike with an older camera, such as the G3. Scrutinizing video monitoring evidence the zoom is still faster, but this 'faster', unlike on the G3, is not observable by me. So this is well within human observation/reaction tolerances and likely of little practical issue.

The 45/1.8 focuses detectably faster on the GX80 than on the G3, if I really pay attention. The 45-175 focuses so fast on both that I find it difficult to tell the difference, with or without DFD. The 20/1.7 is an example which focuses obviously faster on the GX80 than on the G3 on many occasions even if I am not trying to observe the focus speed, so DFD probably makes the most difference on that. However, with DFD, AFC is still disabled with that lens.

DFD basically mimics PDAF, but current Pana CDAF is so good that you may not need PDAF in most cases. On the other hand, if you use FT SLR lenses or any other SLR AF lenses via AF-capable adapters, you should go to the E-M1.2.

One of the sacrifices that they made to make CAF so fast is to occasionally allow unfocused shots go through in focus priority with SAF. But this seems to be a trend with all brands these days. Let's go fast, screw dependability.