Dunno. Good questions, though.

I have chronic and occasionally severe neck pain from a damaged C2, courtesy of a driver who t-boned my car in 2001. The other five cracked vertebrae seemed to heal with less residual pain. But the neck always hurts.

For years I lived on a diet of ibuprofen and coffee, hoping to avoid the prescription pain relievers. Now I'm cutting way back on the ibuprofen, after realizing I was taking around 1,000 of 'em a year. Since resuming cycling a couple of years ago, some days I can do without any ibuprofen. Other days -- specifically, this entire week -- I'm taking 400-800mg a day. Current research says NSAIDs interfere with prostaglandins that promote natural pain relief and healing. Good theory. Someone notify my body, quick.

I can manage 20-30 miles on my road bike, usually in a single session with no stops or only a very brief breather after hard (for me) climbs. Beyond that it gets painful. On 40-65 mile rides I drag home the last 10 or so miles and need a couple of days off the bike to recover.

But during those first 20-30 miles, it feels pretty good. Whatever it is the body produces in these conditions -- dopamine, serotonin, oxytocin, endorphins, mojo -- it helps during that ride and few hours afterward. The problem is those first 20-30 miles always fool me into thinking we can keep going and enjoy another 20-30 miles. Never works out that way. Hence, my oft delayed plan to ride a standard century -- although I've done a few metric centuries.

So until the neck eases up I'm back on the hybrid. Made some changes there. For a year I needed a slight riser bar with a little back sweep. Now I'm back on the flat bar at saddle height. Compared with the road bike, the flat bar hybrid feels like my upright comfort hybrid did in 2015. It's a little slower, catching more breeze on the open rural highways I ride, but I can often ride all day with only some discomfort but no serious pain. And the hybrid encourages me to take it easier, a little slower pace, more frequent rest breaks to stretch.

Yeah, I think about recumbents too. If my neck continues to deteriorate I may have no choice some day. But that day isn't here yet. I prefer the traditional bike for the reasons you mentioned -- higher profile in traffic, better visibility. And while recumbents seem fine on flats and a blast on downhills, so far I haven't seen one that can pass me on hills -- and I'm a slowpoke on hills, usually at the end of the pack in fast groups. While it's not really about speed, I'm uncomfortable crawling uphill at less than 10 mph in traffic. Around 15 mph feels like the sweet spot for comparative safety when being overtaken by vehicles on rural highways and city streets.