I use my work laptop because I have an iMac with a huge screen at home where I do most of my personal stuff (personal dev, licensed software I use outside of work, accounting, storage, etc)... I end up having to synch both machines anyway when I'm on the go since I only have one laptop. Most of that synch comes from the cloud anyway. The benefit of having one single laptop is that you can switch contexts when you're traveling, etc. You can connect with work while doing your personal stuff. The iMac is where I store all my personal files like photos, etc.

If you need a second machine for personal stuff I'd highly recommend a larger screen. A desktop machine seems to be a great add-on to your life.