Considering creating a fusion drive .... questions

Hi,

I'm interested in creating a fusion drive on an older Mac using these instructions:
http://blog.macsales.com/17624-os-x...tup-option-for-non-fusion-drive-equipped-macs

However, I have some questions beforehand:

- This will still work under 10.9 won't it?
- What happens if one of the hard drives fails, can I simply replace the faulty drive and restore from a backup (clone or time machine) the required data?
- If the SSD (with the OS) fails, would I have to create a fusion drive again before installing the OS?
- I use a Crucial M4 SSD. Should trim be enabled in a fusion drive (I have it enabled now in a two-drive setup).
- Is such an installation recommended or am I asking for trouble?
- I currently have the SSD in the hard drive enclosure and the HDD in an optibay. Is this the recommended way?

Thanks,