I would like to know this as well. Also, it was mentioned that you can remove the mods from the BM gear before you trade it in for the WH piece, but is this what most people are doing, is it worth keeping the BM mods seeing as you are getting lvl 61 mods in the WH gear?
The only gear you can trade in for WH is the Purple BM you got from the vendor, not the orange stuff people craft. That is just for aesthetics. In other words, they make you grind and buy the BM before you can buy the WH.
Yes you CAN remove mods and enhancements from the BM gear before turning it in. At the end of the day, those mods are still better than what you may find on the GTN, and people like to throw them in the "exalted" orange bracers/belts to min/max certain stats like power etc.