this is a question your tuner should be able to answer rather nicely.
electronic boost controllers have been proven time and time again at being better at managing boost curves than bleed valves.
that being said, the turbotech manual boost controller has received a lot of praise from a shit load of people for its ability to maintain boost. i think because unlike a bleed valve, it doesnt allow air to bleed slowly to the wastegate (hence its name, "bleed valve") which can cause spiking, but snaps open and allows all the air to hit the wastegate at once when it reaches the pressure you set it at.
in short, get an ebc.
adrian, google -> careerone -> criteria: apprentice, paint.