it was once said in the adult industry back in 1997 on my icq
"imagine its raining money. Do you want one medium sized bucket, or a whole shitload of smaller ones, to catch that money in?"
I thought about it and at the time went for the one medium sized bucket. I've paid for that decision for years.
There is nothing wrong with running several blogs, hosted at several places. Blogger, live journal, kblogger, yahoo, your own server... and interlinking them all.
As long as you're willing to keep them updated, go for both
