Regarding the laptop, if ever I needed to bring it home from work or from home to work I use my back-pack. I feel the laptop at my back is subjected to less vibrations than the laptop on the pannier.

That being said, I very rarely need to bring the laptop home mainly because I could remote (remote desktop via VPN) to it from my home computer if I need to work from home. This also means I don't need to bring any documents with me as I could just easily access them anywhere. If I needed to access data or do presentations on my computer from the boardroom, I just "remote" to it from another computer already in the boardroom. No need to bring it with me... all I usually carry with me (everywhere) is my smartphone.

If I need to backup a huge file (such as a copy of a Virtual Machine), I have a 16 GB USB stick for that.