I have to point out that the question you're asking is flawed, because no one, other than yourself, can determine whether or not it's going to be worth your time and money to multibox. I'm not trying to sound like a dick, and I always say this because people tend to read into my posts, but we cannot tell you how to spend your time, your money, or if you'll be satisfied after you do so.

You've obviously multiboxed in the past, so I guess the question is... Did you find it to be worth it then? Did you find it to be enjoyable? If you can afford $75/month (assuming five accounts), or you've got the time to farm for gold to pay for subscriptions that way, and you find the playstyle to be enjoyable, then I would assume you can probably come to a conclusion based on that criteria alone.

So, I guess it's settled... Fire up those accounts, and get your ass in game!