Surly Straggler good for centuries?

Hi all. I don't currently own a Surly, but hopefully you guys can provide some advice. I'm training for a century and currently own a flat bar aluminum hybrid bike (Giant Fastroad AR). I'm looking to invest in a road or gravel bike that will be better for longer rides. I'm torn between a carbon fiber bike like a Giant Revolt, or a steel frame like a Surly Straggler. I'm also a bigger guy at 6'4" and 275. I would be riding about 90% on pavement, and I would be doing some rides with significant altitude gain. I would be doing day rides rather than bikepacking.

Would the Surly Straggler be a good bike for my use case? Is the extra weight of a steel frame a big disadvantage on long rides or steep hills?