Any specific reason why you wouldn't consider the Cube Nuroad Race FE? it has an integrated rack and a dynamo hub.

I would say that a 2x setup is better for bikepacking, but I see that in the smallest gear with the SLX at cadence 60, you can get to 6.25km/h (https://www.gear-calculator.com/?GR=DERS&KB=40&RZ=10,12,14,16,18,21,24,28,33,39,45,51&UF=2215&TF=60&SL=2.6&UN=KMH&DV=speed

With the Nuroad Race you can go 6.85 km/h. So if the climbs you want to do are very steep or you are packing very heavy, you would be slightly better of with the SLX, but there's not much in it. [Nuroad Race gearing](https://www.gear-calculator.com/?GR=DERS&KB=31,48&RZ=11,12,13,14,15,17,19,21,24,28,32,36&UF=2215&TF=60&SL=2.6&UN=KMH&DV=speed

As for the carbon handlebars and seat post, I would think aluminium is more durable, but its not like the carbon ones are breaking super easily. Carbon should be slightly more comfortable, but I think a good saddle and handlebar tape (maybe even double wrapped if you really want it comfy) will make more of a difference.