Using Blogger to take notes

Last semester, I took notes in class by making comments in pdf files. I'm considering using Blogger (this site) to take notes next semester for these reasons:

• Automatic saving and backup
• Easy searching by date or tag
• Automatic archiving - I don't need to scan notes or upload them

But I'm being wary of these:

• Requires Internet access
• Cannot draw diagrams easily (applies to all notes on computers)
• Must ensure blog is private