Blue -- Good questions. I think that I have an appreciation of what you are looking for.
Personally I'm not concerned about just about any frame breaking, inc carbon. Some folks here say carbon falls apart. not true. nothing weak about Al or Ti either. you can expect any frame to last for decades, even touring. Surly makes their frames extra heavy. This will affect ride quality. If you can tell the ride quality difference between a $500 and $2K road frame and appreciate that difference. I'll suggest that you will tell the difference between similar priced touring frames, loaded or unloaded. There's a lot of bicycles out there set up similar to the Straggler, but probably with better ride qualities. If you are stuck on steel look at the Co-motion duschutes. Personally I really like the ride quality of carbon, smoother and just as responsive, plenty strong. There's several "adventure" bicycles around in carbon, probably in your price range. And more suited to Di2 triple if you ever go that way. Since this bicycle will also be for commuting and day rides take those needs in mind also. A heavy steel bicycle might not be the best for those uses. The person was right about needing internal routing if you go Di2. I've heard good things about Lynskey for TI. Don't sell yourself short, get a bicycle that rides well if you appreciate that difference. Thanks!
Good luck in your search.