I had the G1800 wheelset, the budget version of the GR1600 and the R32 (P1800 now). I had a lot of miles on on the R32 wheelset and it was flawless after a lot of abuse (and I’ve broken road wheelsets). The G1800 has a fairly flexible rim vertically (I think), but I believe the GR rim is stronger because of the different joint.
The 350 hub is going to be near silent or silent (with the 18t ratchet). This is awesome. The G series wheels use a heavy duty 2.3mm “wide” version of the road aero spokes, so they’ll be stronger than the Fulcrum 2.0mm round (DT Competition equivalent) spokes. The similar CR wheelset is a touch narrower and would also be a great choice if it’s cheaper (doesn’t come with an XD driver though).
The fulcrum’s machined rim by the nipples looks cooler.
A few things you might not have considered -
-(If you don’t buy these wheelset from Merlin)- these will come with about $80 in adapters you can sell on ebay (end caps, XDR driver, 6-bolt disc adapters). List here - DT Swiss GR 1600 Spline® 25 28" Disc Wheelset Wheel Sets | Bike-Discount
-The DT Swiss hub is super common, doesn’t require any tools to remove the cassette - this means you can EASILY share a cassette / freehub between two wheelsets if you have more than one. The hubs, being super common, make it easier for the discs/cassette to line up between the sets.
-With a 28mm tire, the DT wheelset will be somewhat aero. The Fulcrum, not so much.
-Dont bother with the “Upgrade” ratchets. They make more noise, cost money, and only make a difference if you’re going really slow. The engagement difference is minuscule in any normal gear. Not worth the money or noise tradeoff.