I was surprised to find the narrowest, lightest weight razor is my fav so far.

The flexibility that I have refered to is not exactly related to the grind or original design. For instance a new razor properly honed by a skilled person gives you the typical flex at the edge per design.

prematurely thin the spine by 2mm for example and the bevel extends much further, bevel is much thinner near edge offering less support allowing the edge to flex more-- that is the flex I am concerned with. Still not an issue?

or by artifically raising the hone angle one could add support the the 0 edge with thicker material- which may not be needed unless condition above is relevant