About a year and a half ago, I was using LiveDrive. Since then, I've decided to switch to CrashPlan. Why? For one thing, LiveDrive was consistently uploading at a pace around 300KB/second. I appreciate the fact that they're in the UK and if anything ever happens to the US, I know that my data is safe in England :) However, uploading gigabytes at that speed takes forever. Another reason is that their Mac support totally sucks. Can't say how much it sucks.
I've been using Macs for about two and a half years now and really love how I can do just about everything with it. Most programming languages are available on Mac and if it isn't, I can easily create a VM. Right now, I have about 8 VMs in various OSes and environments. I can experiment with technologies so easily. I've basically decided that for my work and research, I wouldn't use anything else. I've made the switch and I'm not going back. I have some older laptops that are Windows based and when they die, I'm going to replace them with Macs.
My server is still Windows based and that's mostly for ease of management. Although I'm starting to rethink that decision as well. My main purpose for it is to serve files, so I may just get a dedicated NAS. Then the other purpose for the machine is to host VMs. I can do that just as easily with Virtual Box on a Linux machine. A reason to keep the machine around as Windows is gaming.
In any case, support for Mac backups has become very important to me. I have stuff on my machine that I want backed up. I have a time machine, but I want something offsite. And LiveDrive is NOT it. I do like their briefcase feature, but DropBox works more efficiently. So ultimately, LiveDrive is out and hello CrashPlan! And it is cheaper!