performance on Solaris

Hi, I need to set up a LDAP production server with 800.000 entries. Performance and stability are my main concern, I expect around 250 binds and 50 ldapupdate/insert per minute. The machine is a SunFire6900 with 8 sparc US-IV+ CPUs and I'd like to dedicate around 500MB of ram to OpenLdap (more, if necessary). The OS is SunSolaris 10. I'd like to know if OpenLdap is sincerely a good choice with these numbers, and if anyone can share his on-the-field experience with so many users. Thank you very much, Stefano