This is a hearty thanks to those who responded to my posts with guidance and suggestions. Without the info from this forum, I would have sold the bike a couple of weeks after buying it. What follows is a brief chronological account of my "journey" with my 451 Quest.
1) I installed the longer chainstay. This was transformative; I have size 12 feet and had issues with heel strike on the click box. Once I installed this (twice as you can read the thread above) I felt that I could be comfortable on this bike.
2) I inclined the seat back as far as possible.
3) I eliminated a minor irritant by installing a small block of wood between the kickstand and the frame. The kickstand was too short to reach the ground and this solved the problem. I had to buy a longer bolt , 45 cents, to do this.
4) I installed an adjustable stem and bar ends. The stem is pointed as straight up as possible and has eliminated the issue of hitting my legs on the underside of the handlebars.
5) I bought a Ventisit pad. After reclining the seat back, the original pad was ok, but the Ventisit............. aaaah, really comfortable.
The bike is a keeper. Originally I'd planned to keep my Burley Django and ride that occasionally, but when I got on after 5 weeks of riding only the Quest, I wobbled almost as badly as I did initially on the Quest. I was really shocked at that. Muscle memory betrayed me.
At some point in the future I'll replace the rear shock because of the squeaking. It functions fine, but I can't get rid of the squeak. I have no plans to go to larger wheels or change the gearing. The Dual Drive is a great choice for the type of riding I do. And I like the elliptical chain ring; I rode Shimano elliptical rings on my Cannondale from '85 to '95 so I might be biased.
For new riders I would say: stick with it, handling will become natural and you have an ally in the forum members.