I actualy run a 1-piece on my ~420rwhp twin turbo and I have had no issues with it after 35k miles of hard driving. I was going to replace the bearing but I am always trying to eliminate points of failure on my Z so I ended up going with the 1-piece. I have been very satisified and have no vibrations or other ill effects.
If money is an issue, go for the cheapest but still quality fix, easy solution.