An 8gb 133-speed CF card costs £8. An CF to IDE adaptor is £1.30. Put them together and you have, in theory, an 8gb IDE hard drive for £10 which should be very fast, since it's actually just memory.
So I did exactly that, and tried to install Linux on it. After six attempts, I concluded that it just wasn't going to work. But as I sadly took things apart, I noticed that I could see through the IDE cable in places. So I replaced that, and then the install worked just fine! It was a duff cable. The system is using just over half the storage, leaving 2.7 gb for other stuff, although if I use this idea seriously, I'll be adding 3tb Sata drives for storage.
The best part of this is that wearing-out hard drives is one of the top three causes of computers going down, in my experience (the other two are cpu fan and power supply). It's actually a bit worse than that - if you have a system drive and a data storage drive, then you have a problem if either of the two drives goes down, so that doubles the probability.
How reliable are CF cards? I don't know, other than I've never had a problem with one. But theory tells me that they aren't mechanical, there's no moving parts to wear out.
CF cards to have a limited lifespan, but I don't know what it is. I think I'll be incorporating this adea in future system builds.
I am reminded of the first hard drive I ever bought. I got it from Pete and Pam, the full cost was £1000 (I got it for £650), it was 10 megabytes and it was so heavy (it came with its own power supply and a steel case) that by the time I got it home, my fingers were falling off. I'd guess it weighed 30 pounds or more.
The CF-based thing cost £10, is 800 times more capacious and weighs less than an ounce.
Compare that with cars.
My first car was a Morris Minor, cost £80, did 40 mpg at a top speed of 80mph, 40 years ago. My current car is a Freelander, cost £35,000, does 24 mpg if I'm lucky and has a top speed of 70 mph, because if I go any faster I'll get done.