Opinions on Raid

We have been running Postgres on a 2U server with 2 disks configured in
raid 1 for the os and logs and 4 disks configured in raid 10 for the
data. I have since been told raid 5 would have been a better option
given our usage of Dell equipment and the way they handle raid 10. I
have just a few general questions about raid with respect to Postgres:

[1] What is the performance penalty of software raid over hardware raid?
Is it truly significant? We will be working with 100s of GB to 1-2 TB
of data eventually.

[2] How do people on this list monitor their hardware raid? Thus far we
have used Dell and the only way to easily monitor disk status is to use
their openmanage application. Do other controllers offer easier means
of monitoring individual disks in a raid configuration? It seems one
advantage software raid has is the ease of monitoring.

I truly appreciate any assistance or input. As an additional question,
does anyone have any strong recommendations for vendors that offer both
consulting/training and support? We are currently speaking with Command
Prompt, EnterpriseDB, and Greenplum but I am certainly open to hearing
any other recommendations.

Thanks,

Joe