I m no expert to say the least!years ago I got frustrated tillering reflexexd bows so I really worked on my floor tillering,stopped using a tiller stick.started going from floor tiller to brace and touching up from there.losing half the reflex is not the worst,just is what it is!
I did quit the tiller tree too.
Working as precise as possible
before bending is thing (at least I believe so).
I do all my floor tiller horizontally, hanging the tiller string on a hook in my vice and crabbing the bow with my right hand and slip the left over the limbs to feel the bending (not only seeing, esp with character staves).
This way you can handle even pronounced reflexed staves because your hand prevents the torque. Another good thing is you can feel the string tracking. Switch the bow (so that you have the upper limb once on the left and once on the right side), if the pulling shows a different behavier, the string aglinment is off. I have done bows (unbacked) with really heavy reflex.
Here is an exaple of a bow that still holds a reflex of 6½", after lot of use:
http://primitive-bows.com/sister-statics-no-7374-part-2/Hope that helps.