Valor req's 165 Str which is ALOT and it makes your Sorceress slow and your cast rate delays so if you get in a tight jam, you wont be able to tele fast out of it. And on a further note, personally I say for PvM Stormshield doesnt compare to Whistans for alot of reasons:
REASON 1:
Whistans Block Rate is ALOT faster so you wont get stunned as much.
REASON 2:
It enables ALOT more vitality.
REASON 3:
It has a shit load of blocking.
REASON 4:
YOu can still get alot of DR with using Whistans and most PvM is elemental.

As for boots, jump on with Stormtrek or Waterwalks.