It is so easy, I find, to get caught up in tillering, and over shoot the desired weight. I have ended up sawing tips off limbs more than once in an effort to regain lost weight
. Sounds like you are doing pretty well.
On English D-section longbows, the lower limb is often a little shorter, and therefore stiffer. On the other hand, on symmetrically tillered flat bows, the lower limb, whichever it is, often takes more set over time than the upper limb (due to bracing techniques, storage and the uneven mechanical effect of nocking the arrow above centre). I have read that the fixes for this include making the lower limb a little longer or a little wider. I am not quite sure what effect you would get, over time, if you left it stiffer. Fractionally stiffer might work, but I can see it would be very easy to get it too stiff and wind up putting the upper limb under more strain, so inducing a set there instead.
I'd be interested to hear what other folk have found about upper/lower limb ballance.