Oracle Parallel Server and 24x7 availability

We are a start-up internet company and need 24x7 availability.

I've been investigating into different options, but so far Parallel Server (OPS) seems to be the best option because at least both instances can be actively used for load-balancing and fail-over.

All other options seem to be expensive (EMC or advanced replication needs a duplicate server)

But, does Parallel server really work as advertised? I've really never heard anything good about it. I've mostly heard that it doesn't work as advertised and the "raw device" requirements make maintenance a big deal.
I've also heard that performance is poor.

So...can I get some responses from people using parallel server? Would you recommend it as a solution fro 24x7?

Any books recommended by anyone that goes through the installation and configuration of parallel server?

We are deploying on Sun Solaris