IMac :: Won't Work With External Hard Drive Hook Up Options

After debating the need vs. want of the iMac and Mac Pro, I'm going to follow my brain and go with the iMac (27" i7) since I use it for work, though my work is in the business side of the music industry dealing more with email, spreadsheets and some minor music/photo/video editing (which is easily done for me via Apple`s iLife).

My real question is with the 3 external hard drives I want to buy - G Tech 1TB G Drives. I read about daisy chaining the drives, which sounds like a good idea. But am curious about it. Obviously if I have 3 external HDD's and want to use FW800 on all three of them, with only one FW800 on my computer, daisy chaining solves the problem. But in this set-up, what is the potential downside to this? Is there an upside or other reason(s) people daisy chain their drives, too?

I`ll use the iMac's HDD, of course. But I also need one HDD for work (important files, contracts, etc). One for personal (music, photo, video). And lastly, one as a back-up for the other HDD's.

What would my BEST and also cost effective option be? Buy 3 externals and daisy chain them? Use eSata (what would that entail)? Increased speed would be the only major plus I'm looking for with setting these HDD's up. Just not sure all my options...

But keep in mind I don`t need them to mirror each other. HDD 1 (iMac) has my minor importance stuff. HDD 2 has my work files and business stuff. HDD 3 is personal photos, videos and massive iTunes collection (300gb). And HDD 4 is a back-up of all the others. Raid seems to be not exactly what I need - perhaps overkill on cost, too. What do you think? Also, I know everyone has their taste in externals. I actually had great reliability in Western Digitals MyBook Studios, and My Passbooks. But some people I know had good time with the G Tech`s - aside from them looking cool.