I have been a user of Iphoto for quite a while now. The main issue I have had, is the fact that I take a lot of pictures on my DSLR Nikon D80, so, most of my pics are around 6megs or so in Jpeg, larger if I take RAW shots, and obviously the problem increases if I store JPEGS and RAW shots in iPhoto.
I'm no professional photographer, just a father with a camera, and a lot of pictures
So anyway, my iphoto library grew to 36Gigs. I had been using Mobile Me to backup my iphoto library. This is very easy.
If you go to your Pictures folder, you will see the iPhoto library. If you back this entire file up, and if your computer dies.. you can replace your backed up file with the one that will be installed when you have your fresh iphoto installed. When you replace the old file and then open iPhoto wha bam it is just like old times.. and it keeps all of your albums, events and such.. if you just copy your photos out you will spend the next few days working on your events.
Since my iphoto library is so large, uploading 36 gigs once a month~ish was silly, and burning this large of a file is also silly...
I converted to Aperture. Aperture 3 is just like iPhoto with some nice additions... Folders. I created 4 folders. 2006 photos, 2007-2008, 2009, 2010. I can then add "projects" which for all intensive purposes are "events" in these folders. You can export folders! So, I exported the 2006 folder in a smaller format picture (high enough for printing but small enough for storage) There is a setting to preserve the folders and subfolders in their names, so when you import again, it will keep your organized "projects".
After exporting these 4 chunks, I compressed them, it seemed to decrease the file size by 20%. Now my entire backup is in 4 chunks. Now, I just upload the 2010 folder once a month~ish, because I can split this with Aperture. My compressed library with conversion is around 4 gigs.
I like iPhoto, but Aperture if you can afford it is really the way to go, especially if you take a lot of photos. If your iphoto library is under 10gigs and you are on broadband or have a 16gig thumbdrive, just move your iphoto library over and you are set.. if you are me (30gig+ library), get Aperture.
(If some info here seems redundant, I am more posting it for google searchers. I had spend many evenings searching the best way to back up my photos, hopefully this info will help someone)