Personally i prefer glossy but i think that's just personal preference. I'm not 100% sure but i could imagine that dust sticks to a matte surface a little easier and a glossy frame would be easier to clean. Not sure though. My Velobuild VB 268 is pearl white glossy. You can check it out i posted it in the VB 268 thread.

Regarding my R088: I did another ride today. 30 km with around 500 m of elevation. I felt really comfortable climbing. When descending the bike was really fast. My brother rode next to me on my gravel bike almost spinning out and i was just rolling there comfortably. I think the 50 mm wheels play a part in that. The route contains a very rough segment. The strava segment is called "Höllenritt" which literally translates to hellride. It's a -7% descent over the worst road imaginable. Lots of potholes and cracks and overall damaged pavement. If your bike can handle that it can handle literally anything else. And i gotta say the bike handled it really well. The frame and especially the fork seems to absorb a good portion of the bumps. It still feels rough obviously as it's a roadbike but i never had the feeling of losing control over the bike. Really happy with the ride feel overall.

Also managed to take a picture with the bike in the sun, making the carbon layup really stand out: