I've had my FE-02 since October 2021 and have put almost exactly 1,500 miles on it. I initially built it up with 700x42mm tires which handled well but weren't wide enough for the riding I do on this bike, so I swapped to 700x50mm Gravelking SK's which measured about 52mm on 25mm internal rims. This was good volume but put my center of mass too high for comfortable handling, and toe overlap with my size 43 shoes was also really bad with this setup. Currently I'm running 650b with tires still measuring about 52mm, and this is the best compromise for handling and tire volume I've found thus far.
Wheels/tires aside, the geometry is very stable without being too upright, which I like; it's definitely not on the progressive end of the spectrum with respect to headtube/seattube angle or anything, it's much more similar to my road bike than my mountain bike. The handling isn't as razor-sharp as my road bike either, and I wouldn't use this as bike for primarily road riding - I've had my road bike wheels (700x32mm tires) on the FE-02 for winter riding and the handling didn't really change from its 650b setup. Not that the handling is bad, I am using it right now as my main winter ride since it has full length fenders on it, just that I don't have the same sense of being one with the bike that I do on my Tarmac SL6.
Lastly, the construction quality of the frame/fork is very good and I've not had any issues running cables/wires/hoses through the downtube; the chainstays are REALLY narrow so care must be taken not to wedge internal cable routing tools in there (it sucks to get them out....). I've even been able to run a dropper post on it with Di2 - see my post history - and doing this would be even easier with mechanical shifting since there's no battery in the way. The dropper really enhances the ability of this frame to tackle rougher downhill terrain and I find myself using it a lot during regular descents too, as it offers a comfortable yet very aero position. I've ridden this bike on some truly dreadful terrain, including completely offroad bikepacking out in the woods where me + luggage + bike weighed close to 120 kg all told, and it's performed great. The frame isn't light but you get durability in return, it seems.
Overall, I'd definitely recommend this frame if you're in the market for a burly, big-tire-clearance gravel bike.