Thanks for the tips.
One general follow-on question regarding wheel size. Right now I am on a tiny wheeled (12" front, 10" back) 250 cc scooter. At highway speeds it gets a little jittery, and the first time I had to go over an asphalt to concrete seam at an oblique angle at speed (maybe a 1/2" lip at most) I was kinda freaked out though it was not really a problem. Will the front wheel DS 19" vs S 17" make much difference in stability? What about knobby vs. street?
One of my concerns is a funny knee, so I like the idea of a larger knee angle for hour long + rides, which will be rare, but will happen, but I will have to try them both and see what fits MY body. I also have a funky shoulder (welcome, middle age) which makes rolling it forward on the grips not a good idea for wear and tear on the joint (welcome to middle age. Sigh) so that will be a factor too.
I expect I will be getting rid of any knobby tires. No dirt riding planned and I am mostly doing this for the carbon impact. Unless it makes a notic ble difference on asphalt-to-concrete seams on the highway they are going if I get a DSR.
I like the sounds of the rubberized pegs, but pegs seem relatively trivial to change out.
I especially like the idea of extra inches of clearance for lane splitting, and it is more than one or two that will be a factor. I split in crazy silicon valley rush hour street traffic all the time, turning a 3 cycle wait at the light to 1. I imagine I will do it some on highways during stop and go/10-15 mph during rush hour (I will NOT be one of the nuts lane splitting at full speed, with the cars stopped or going 10mph.)
I like the idea of height. I like to see and have a pretty long inseam so will not be tippy toe at the lights, most likely (in fact my extra long sized riding pants do not quite make it to the top of my mid shin boots. Gonna be a problem in the rain. :/ )
These responses give me a good checklist to consider when I try them out.
* Bring a tape measure for width and seat height (specs say 1.4" difference in height, but I am an empirical guy)
* Figure cost of swapping out the knobby tires
* check leg angle
* Think about if look matters to me (95% sure it won't. I am rather a practical type of person)
* Feel out handling differences in a test ride. Agility is always a plus.
thanks again!