Thunder and Lightning and Sun

I see that The Mozilla project has added functionality to Thunderbird, the email client I use. With Sunbird calendar and Lightning plug-in. "Since it's an extension, Lightning is tightly integrated with Thunderbird, allowing it to easily perform email-related calendaring tasks." My question: Is anyone using this combo as a replacement for Microsoft Outlook?

My Outlook pst file is about 1GB and email contents date back to my start in telecom in 2000. Can T-Bird run with 1GB in email, contacts, hundreds of folders, thousands of calendar items and hundreds of tasks and reminders? Any input would be appreciated. Thanks.