We've had the same discussion with our vendor, but they confirmed it is not anymore mandatory.
We always prefer to do the setup ourself to be able to troubleshoot whenever things go wrong. Currently we're having a demo with 2x 3PAR 7200c's at the office. We can test the hard- and software for 3 months without any cost. If you don't like it, you just send it back. Of you do; you can buy the setup you already have. In this period, we'll be breaking and making the setup many times to be sure we are ready for the most common reasons of outages.
I strongly suggest to do a demo before buying anything. You can make yourself comfortable with 3PAR. After setting up, you could ask for a chat with an engineer to be sure you've configured things right. No installation, just a meeting with some handson and best practices material
It's the way how we do it.