NewBike has proven itself good on trails and on the street both, just as I'd hoped. I've been able to extend the distance I can ride on the trails on the land (and thus vary the trails) though I still have to stop every few hundred yards (esp. uphill) to catch my breath. But it doesn't take as long as it did, and I'm able to creep the distance up without exceeding the heart-rate I don't want to exceed (or even reach, most of the time.) I now regularly go out with a tool or two in the back (lopping shears, pruning saw, sack of birdseed) and make use of them for our wildlife management project.
As for street riding, I made it to the Post Office for the first time right before the NYC trip; I put an old briefcase in the back basket to carry the mail back. That was probably less than a half mile round trip.. Yesterday I made it (combining riding on back streets with walking the bike across the highway and downtown, as it's not at all safe to ride there) to the bank (a little over a half mile) and back by another route to the Post Office, then back to our house. Two crossings of the highway, one of Main Street (all walked, and one block of Main walked) and the rest riding. Somewhat more than a mile total. That, plus the morning's "land" ride (a circuit of about a half mile) went well. Today I made the same circuit on the land, and a mile (down the street to Main and back) on pavement. I was able to go the half mile up slope from Main without stopping.
Except for concerns about traffic (and I pick the times of day when traffic is minimal) riding on the street is a lot easier--but riding on the land is more exciting. Will I make that turn? Can I steer accurately in the bumpiest parts? Did I prune that tree up enough, or will it slap me in the face? (That happened once, I missed a turn in the trail and rode right into the cactus-y area. But managed to stop before running over or into any cactus. The tree is now pruned up higher.
So...progress. No pictures yet of the expanded range, or street riding, but maybe in another month.