Thanks for the comments. My current bike is a 1991 Cannondale ST600, 25 inch frame with the same specs that you listed. It is a stable and generally pretty comfortable, somewhat harsh on road bumps, which maybe I could improve with larger tires, but other components also need updating and I think it makes more sense to invest in a new bike for longer rides and keep my Cannondale for shorter rides commuting/around town. I'm also looking for more of an endurance type frame, I'm 57, and planning for a bike I can ride for the next 25 years. Maybe I'm over analysing it, but given the option to customize every dimension of the frame I want to dial it in as much as possible.

I'm still working on the dimensions with Vecchios, and asked them to increase the trail from 58 to 61 mm, also increase the wheel base from 1028 to 1060 (compared to 1085 on my Cannondale), and the new bike will also have higher stack and shorter reach than the Cannondale. I confess I don't know anything about frame design other than what I've read on the internet in the last few weeks, maybe just enough to be dangerous, and I'll rely on Vecchios to stop me from doing anything stupid. I'm hoping the increases in trail and wheelbase makes sense for my priorities for stability and comfort. Thanks.