Question - do most people put their RAW images through DPP?
There are generally three main things you want/need to do with your RAW images:
- Convert from RAW
- Edit/retouch images
- Organize your library
Some programs perform the first three (e.g. Aperture), some perform some of them in combination with other software (e.g. Adobe Camera RAW plugin converts RAW images for Lightroom to organize or for Photoshop to edit), and some do only one (e.g. DxO is only a RAW converter). That's one reason I think DxO is better - it doesn't try to do it all, it does one thing, and does it very well. Personally, I use DxO to convert my RAW images to JPGs, then I use iPhoto to organize the JPGs.
There's also a fourth thing you should do with your RAW images that none of the above-mentioned programs directly handle - backup! Backup! Let me say that again. Backup!
Whatever you do to the processed images, your RAW files should always be backed up - preferebly in more than one place (e.g. two different external HDDs stored in separate locations, or one external HDD and an online backup service, etc.). Depending on your RAW conversion software, you may also want to backup the settings used for the conversion for each file. The way you do that will depend on the software. DPP (alone of the RAW converters) writes the changes directly into the RAW metadata, so all you need to backup is the RAW files themselves. Most other programs store the settings in a 'sidecar' file linked to the RAW file; you may need to export those sidecar files, or backup the whole database, etc.
Are you guys aware of differences in IQ in particular between the different RAW Decoders (DPP, LR; Ap, whoever) set at similar presets?
Yes, there are differences. I used to use DPP, then I switched to DxO Optics Pro. I find that DxO does a much better job than DPP at reducing noise, and DxO also offers lens-specific corrections for distortion and vignetting (like DPP, but from my testing the DxO corrections are better than Canon's own). Other RAW conversion software has lens corrections (e.g. Adobe Camera RAW) but DxO's are based on actual empirical tests of specific camera+lens combinations, whereas ACR's are based on 'what looks good' and in some cases are actually derived from user-submitted profiles.