RAID Controllers

I'm buying a bunch of new machines (all will run an application that heavily
writes to PG). These machines will have 2 spindle groups in a RAID-1 config.
Drives will be either 15K SAS, or 10K SATA (I haven't decided if it is
better
to buy the faster drives, or drives that are identical to the ones we are
already running in our production servers, thus achieving commonality in
spares across all machines).

Controller choice looks to be between Adaptec 6405, with the
supercapacitor unit;
or LSI 9260-4i with its BBU. Price is roughly the same.

Would be grateful for any thoughts on this choice.

Thanks.