I've owned both the Burton Mission bindings (two seeason ago) and the
Salomon SP4s (now). I actually had the exact oppositve problem... I
had Burton Missions on a Salomon board and wanted shift the bindings
along the longitudinal axis (nose to tail - you seem to be calling
this front to rear). However, the Burton plates only allowed for
toeside/heelside adjustment... to fix this I simply rotated the plate
90 degree and voila! Now I'm not sure what disk your SP5 came with,
but I just checked my SP4's and they can definitely do this... even
more so they looked like they are designed with this in mind because
the angle indicators have "0" degrees in all four directions...
compared to my Burtons which I had to "scratch/cut" in new angle
markers at the 90 degree locations. Are the SPX5 disc unable to be
rotated 90 degrees?

I do actually feel a little like you in that my heelside transition
doesn't feel as instantaeous as my toeside... slow and awkward even...
maybe I should try it too... however - reading your post, one thing
that caught my eye is that your are increasing the forward lean on
your *back* foot. Increasing the forward lean of your highback does
help your heelsides (I have mine nearly at the max). However, when
initiating you heelside turn, you are mainly using your *front*
binding to bring the heelside edge (right behind the nose) into the
snow. So you would need to crank up the forward lean on the front
binding to transition to heelsides more quickly - especially if the
board isn't particularly torsionally stiff (although I think the
recent Burton Custom models are pretty good).

Anyways... let me know how it goes... good luck!
--Arvin

I own a pair of sp3s and had the same need for heel/toe adjustment as Juan,
and as Arvin suggests I rotated the plates 90degs (I had a Salomon board).
I think the problem is that due to the lack of rotational symetry in the
Burton 3D system, the plates are only compatible with Burton boards at one
angle, and unfortunately that's the position that gives you tip/tail
adjustment but not heel/toe.

S