The +Evasion bumps the C- rating to a C+, and with 4/4 merits, gives you an overall cap of 238 which is almost a B-. Basically, when gearing for evasion, these are an amazing help.
These boots are also helpful in a party situation where you may be pulling hate off the tank. BLU spells start hitting colibri really hard around level 57, and the -3 enmity can help save your healer a bit of a headache.
I realize that your comment is 3 years old and a lot has changed, but I assure you that having a proper evasion set greatly increases a BLU's survivability. Tried a hybrid EVA/TP set without these, getting hit really hard by some NMs, swapped this into the set and could see the difference right away. Great for soloing