I'm using a backup scenario which uses swapping out mirrors (RAID 1) in combination with Windows Volume Shadow Copy services. Twice per day my system (Server 2003 or Server 2008) takes a Volume Shadow snapshot (VSS?), which is how you get that "oops" protection - its similar to having an always available, instant restore tape library built right into the filesystem (BTW, Novell had this feature 10 or more years before Microsoft, but I digress). You just need to make sure you have plenty of free space on the drive to accommodate the snapshots, but the algorithm is very efficient since it only grows when files have changed.
Then, once per week, for the off-site disaster protection, I swap the external eSATA software mirror drive out, remove the broken mirror under disk manager, import the foreign disk from last week and recreate the mirror. Bingo - just a single drive to keep up with. I have a hot on-site mirror and an offsite mirror no more than a week old. Its quick and convenient and performance is excellent (and cost is minimal since the features are built-in to Windows)

I'm not sure if there's an equivalent to Volume Shadow Copies under Linux, but the software mirroring is there and works quite well.

Whoa, hold the boat. I've had a lot of experience with Dell & HP/Compaq(Proliant) provided RAID systems and they are not sensitive to disks with vastly different innards. All that matters is block count and software mirroring doesn't even care about that, because you'll simply be limited to the size of the smaller disk. If you're using mirroring or RAID, try to go with different makes of the same size. This article talks about MTBF. It turns out if 2 drives of the same exact model comes off the line and end up in your PC, there is a chance they could fail within a very close time to one another. So your mirror or RAID could fail permanently while rebuilding from the first failure. But if all your drives are of a different make, chances are they won't fail at the same time and you'll get the critical time needed to rebuild your array.

When I'm going to do mirroring or RAID on hardware that doesn't have high-end dedicated server RAID controller, I use Windows or Linux software RAID. Performance is surprisingly good and I'm not married to a specific hardware implementation. I've had _none_ of the issues you've described with Linux software RAID on several servers for several years. Mdadm has only whined after a power outage or genuine disk failure.