Has any one ridden the East Coast Greenway?

No I have not. My touring group were eyeing it when we did a lot of riding about 10+ years ago but we never pursued it and it wasn't done. Looks pretty cool. The last trail we did was to connect to Waterfront Trail (left upstate ny and went through the freaking mountains of thousand islands then connect with waterfront trail). It was interesting - I had all the research (like bike shops in the towns etc) and maps - but there were times when for ex this one stretch - there was NO shoulder - just large rocks and the narrow highway that was full of 5 o'clock traffic. We watched one bicyclist do it and we said no way and we walked our bikes. Another time the trail skinnied out and we were riding on a 6" wide dirt pat in a field of high weeds. Met a park ranger in a truck in the field (odd) and he said yep, that's the trail. Couple other times GPS or no GPS, we hiked our bikes up embankments to a real road. But all in all it was fun. Would love to read your traveling blog on that trip!

wow - never saw anyone tour on a tall bike! Did see one oddity - this guy coming down the road with backpack and stuff and all his stuff was in large black garbage bags. You could not see the bike or his legs. In fact he was rather a large black circle pedaling down the road.

I've ridden parts of it from NYC to DC. Some parts are nice trails or paved paths and others you're riding in the road with traffic or on the shoulder. I would definitely recommend thicker tires as most of the shoulders are covered in debris.
Much respect for the tall bike touring, my touring buddy and I have considered riding the C&O trail from DC to Cumberland MD on our tall bikes. I've never tested out riding with racks or panniers on my tall bike but I'd assume weight distribution is the major issue to not topple over.
If you get to Philly in the next two weeks hit me up, I'm leaving around the 20th.

Def gonna want a map, at least from my experience in the NYC-MA route. Signage can be confusing or absent. But the ride is good!

Everytime y'all say tallbike, non-rider me sees this:
View attachment 32810
Definitely would be a challenge around traffic xD

Just found about about this gem! Ridin part if it now to baltimore.. Just rode the gap and c & o towpath to dc from pittsburgh. Though traffic can get weird, the paved path is a welcomed change from the rooty & rocky c & o!