Instead of catching the magazine - providing that it's empty - I simply train to rip out the magazine proactively if I have two hands in-play. This would be just ike the empty magazine scenario that you played out above.
It's a trade of a couple of seconds here for a couple of seconds there - it's hard to say what's going to be better given any one situation, but at least I know for sure that the spent mag will be out of the gun before I bring up the incoming.
It's just my personal preference, and it's a personal preference based on how my EDC sometimes unreliably decides to not drop free its drop-free magazine - something that's no fault of the gun or the mag, but rather, with how my dominant hand interacts with the gun/mag.
The bonus to having this primacy is better ingrained physical memory for double-feed stoppage reduction.
Oh, and as for those who prefer the one-handed method?
With drop-free magazines, it's always worth remembering that it's intended to work with gravity, not against it - at least initiating the drop while the magazine is still perpendicular to the ground will help its successful ejection from the gun. Sometimes, a quick flick of the wrist can also help eject the magazine via centrifugal force, as can a quick downward (towards the ground) "hammer-punch" motion via inertia.
If/When one finds that the spent magazine is still in the gun, there's no need to panic, simply use the incoming magazine body to "strike out" the resident mag, and carry on. Here's where I'm trying to save that second or so - for me, it's worth knowing that my incoming has a home to go to, but again, that's just IMHO and my preference...YMMV.