While i have done turbos with the engine in i was very dissatisfied with the process. i took way longer than it should and there are a few things i could not do while i was "in there". If i had to do this to a virgin engine i would definately pull the motor.
Even at my slow pace i can pull the motor in a day now. I prefer to take my time with the deletes and timing and fitting everything back so that takes 2x as long. In the end however i have more confidence in the work and thats worth a lot to me.