My $0.002.
The entire last season and the last 5 weeks I experimented a lot with some different combination possibilities.
I tried:
TD2 Step-in w/ Indy and UPZ
TD2 Regular w/ Indy
TD2 Regular w/ Burton Fire, Ice and Indy
Catek Step-in w/ Burton Fire, Ice and Indy
F2 Titanium Step-in w/ Burton Fire, Ice, Indy and UPZ’s
F2 Titanium Regular w/ Burton Fire, Ice, Indy, UPZ’s and Northwave .900
And to make a long story short, "I" liked the softer bindings with the medium-stiff boot the most.
So basically a bail binding with the Indy.
I found the step-ins to stiff for "me", especially in terms of lateral stiffness.
I believe that this had also to do with my body-structure/weight. I think it just makes sense,
that a guy with 180lbs. or more bends the bindings easier than a guy with 170lbs. or less.
Now the question is, do you want, or like the bindings to bend and if so, by how much.
This is what I believe. The harder you ride (especially under not so perfect conditions) and the
lower you lay it down, the more flex you want/need to get from your bindings. I believe that
people who are not in the 180lbs+ range should give it a try and directly compare/ride step-ins
and regular bail bindings under the same exact conditions.
Off course, it also plays a big role what your riding style is. When I was just cruising, I had no
issues at all with the stiff to very stiff set-up. But as soon as I started to really bend that board and
squeezed it and layed it down to the max, the softer bail binding was way more comfortable to ride but
even more important delivered much better edge hold.
This probably due to the fact that most of the energy gets absorbed in the bindings and not in the boot/legs... back to Phil's theory.
But again, I am also not the tallest and heaviest guy (5'7 / 170) and this is just "my" experience I like to share.