NEDIVER

I will start off with a little review of the Aperture software. This amazing for work flow. You can add different key words as you import and sort everything into categories as you import them. You can then make "smart albums" that will pick and choose criteria of all of your files. It stores tons of Meta data and is terrific for keeping large files at your finger tips.
The second thing that I love about it is that unlike Adobe light room or Photoshop, you have only one master file per original shot. What this means is that you may make thousands of adjustments and make hundreds of different versions of the original all while only taking up as much disk space as the original file. It does this by the process being command based. Basically you have your original (negative if you will) and then all of the versions and adjustments are made on screen with commands off the negative. Your hard drive stays clutter free and every change is fully reversible.
The RAW format is terrific as well. you can make very powerful corrections to include, histogram value changes, spot corrections, highlights and shadows (my favorite) and individual color adjustments (great for underwater correction), you can also simulate different filters on the lens with a RAW picture, and convert into true B&W with great contrast. It only gets better from here. With direct compatibility with Photoshop you can export a file directly to Photoshop and back again with ease.
It has wonderful on screen proofing, I calibrate with EyeOne, and then downloaded the correct values for the paper I am printing with and the printer that I use (Epsom R1800) and the screen will look exactly like the print. This is very useful when printing from high glossy to a matte. You can also down load any third party printing service values. This way if you are sending off files to a online printing service you will be able to see what the picture looks like BEFORE printing and make adjustments accordingly.
There are other useful features that allow you to create a book (much nicer than iphoto) and does not include large apple logo's when printed, remember this is their professional software.
If you purchase this software, I would suggest joining the aperture users professional network (AUPN). The membership pays for itself with full day long seminars that they do on a local "tour" basis. I went to one this winter in Boston and it was great.
As far as redundancy of back up, it is a snap with Aperture. If you are running TimeMachine make sure you set it up so it DOES NOT back up Aperture vault. This was a glitch in the Time Machine software that has caused some problems. Once you know that it is flawless. I save all of my master files on my HD and then use the "Vault". This Vault is connected to a FireWire 800, MyBook 500GB external HD. This way all of my masters and adjustments are backed up with one click. Remember that it only takes up the space of the original images and a small file of commands for the adjustments. Then when you Save the Vault after a new project is imported or more adjustments are made, it checks the data that the Vault has and only make the new changes, saving TONS of space.
I could go on about the export ability to put the picture in almost any form and size, and its compatibility with iMovie for slide shows and the like. I can say that I for see no use for Photoshop in my immediate future, unless I want to do advertisement or the like.

TM