High Availability: Hot Standby vs. Warm Standby

Hi,

we are contemplating the possibilities for a Postgres HA installation.

As the rollout is targeted towards the end of the year, 9.0 and it's new features might be an option for us.

Now from a HA point of view, what is the major difference between 9.0's Hot Standby and 8.x's Warm Standby?

I am aware that I can use the 9.0 standby server for read only queries, but that is (currently) not something we need

I'm wondering about the differences when the failover situation occurs. From reading the docs, I get the impression that 9.0's streaming replication might be faster than 8.4's WAL shipping, but otherwise offers the same level of data protection.

Is there a difference in how much data could potentially be lost in case of a failover?
E.g. because 9.0 replicates the changes quicker than 8.4?

If there is no (big) difference in reliability (or potential data loss) I would rather go for 8.4 than 9.0 just because the feature is so new in 9.0 and might not be 100% reliable at the beginning.

Any input is highly appreciated.

Thanks in advance
Thomas