Interestingly, this is apparently a phased project; they started retracking Zeus this year.
I think this could be really good for the ride, personally! I haven’t ridden Zeus, admittedly, but if Zeus is anything like Megafobia (they’re often compared), then this refurbishment should help remove the “rickety” edge from the ride and make it smoother and more rerideable!
I’ve done one coaster with the GG Timberliners (Mine Blower), and while I’ll admit I prefer the GCI Millennium Flyers due to the restraints feeling a little tight in the GG trains, the trains seemed to track relatively well on Mine Blower compared to PTCs (even though I’ve heard a lot of people say that Blower is rough, I honestly don’t remember it being much, if at all, rougher than Wicker Man, and I have a pretty low roughness tolerance. Admittedly, that was in the front, but I can only speak from my own experience); the articulated train design (in the case of both GCI and GG) makes for relatively smooth tracking and nice fluid transitions compared to the slightly clumsier way in which the PTCs track.