Ordered mine. Looking forward to how this feels.
I like the shape of the section of the Eco. If I hold it in a basic tripod position against the lips at the narrowest point it is too narrow. But then, due to adjustments I made to my grip trying to hold the safari, I relaxed my tripod grip to relax and extend the pointer finger still resting against the lip and relaxed the thumb back higher up on the section and the Eco became a very comfortable pen for me and allowed me to use it as a workhorse pen I could use for long writing sessions with a relaxed grip.
I still sometimes use the basic tripod/pincer position and hold it up higher on the section, by with my new relaxed tripod grip I became a rejuvenated fan of the Eco and really appreciated the section and how it allowed me to relax my hand into a comfortable grip on the pen, and now am happy to see if the added facets provide a more secure grip. And since the nib and feed aren't fixed, it allows for that necessary adjustment if needed where the Safari really prevented me from relaxing into my grip unless I used a broader nib.
If TWSBI did well on the design of the section I think this pen has some high potential but I don't want to get ahead of myself.