The CAAD8 has a short wheel base racing geometry. This means responsive (twitchy) steering and an aggressive posture. I can see where that might be unsettling to some riders.I can see that, but I don't see how a bike that he rides OK around home suddenly feels unsafe on a supported tour. I guess he might be planning to carry a bunch of gear even though the tour is supported. Perhaps it is the extra weight.
I generally feel safer with a more responsive bike, but I guess not everyone feels that way.
I can see where that would be fine and then rider ages out of that being fine. I can also see where that would be fine for club and event rides but not I am going to cover 75 miles a day for the next 12 weeks.Aging out? Maybe. We don't know the OPs age, but I have seen no sign of aging out in myself at almost 65. In 10 years, maybe?
My thought was always that on a long tour is when I am most likely to be fully acclimated to the bike and most appreciate the more efficient posture. Again, YMMV.
I think the bigger question is why the LHT will not do for a tour.Everyone is different, to me the LHT is more of a tank than I would want even for heavy touring. I'd rule it out entirely for me. On the other hand for someone who feels uncomfortable and unsafe on a road bike, I'd think the LHT might make sense.
I have an old Paramount Series 3 that I ride. It has a short wheelbase racing geometry, and the position is not too aggressive for me. I could ride this bike every day and be happy riding it. One of my buddies was trying to lure is wife into riding with him, and I let her ride my Paramount as it was about the right size for her. She did not enjoy the experience as the steering was too responsive for her. From remarks the OP has made it sounds like overly responsive steering is not his issue with the CAAD8. I also have a VooDoo mountain bike that I now mostly use as my winter bike. The ride position is pretty aggressive, and if my weight gets over a certain number then the ride position is not that comfortable. I said "age out" but I meant a multitude of reasons for why a bike with an aggressive posture could no longer be comfortable. If you are 65 and agile then you are truly lucky. I am 57 and have to listen to complaints from more sedentary 40 somethings about all their aches and pains. For whatever reason, the OP thinks his CAAD8 will not be comfortable on a Southern Tier ride.
I guess I missed the ride being sagged.
I don't ride my touring bike as much for every day riding as I used to. I find racks and fenders noisy and those touring capable wheels are awfully slow to spin up when you are trying to chase 20 somethings on their zippy fast bikes.
So I could see a need for a road bike with a more relaxed ride geometry, but I still think a Titanium frame is over kill.
I think you can never have too many bikes, and I want non-racing, back road/gravel grinder road bike (as soon as I can talk my wife into letting me buy it).