I read that the 5g is unable to take the 240gb while the 5.5 is able to.
Also, is the included backplate in that package sufficient to accomodate the hdd or do I have to get another?
Any explanation for that and what happens if I use it on my 5g anyway?
I recently bought a 120GB HDD off ebay for $80 and replaced the old 30GB of my iPod 5g. Everything works like a charm with the rockbox installed. I was little concerned about the possible lag before the upgrade but there is absolutely no lag whatsoever. I can't be more happy about upgrading the HDD. The 120GB is decent for me and I have loaded 90% so far.
You can buy an used and working ipod 5.5g off craiglist for a very cheap price. I recently bought a working 5.5g off craiglist for $30 as a backup. Most people selling the 5g/5.5g just want to unload the old pods without knowing the inside beauty (wolfson). Alternatively you can also buy the 5.5g from ebay. If you want to take a chance, buy the broken ones hopefully with only failed HDD and you will replace the HDD anyway.
The 240GB HDD's are available from ebay and here is one. Please note the 5g/5.5g 30GB model needs new and thicker back plate if you decide to go with the 240GB HDD. The seller in that link actually includes this new back plate for the upgrade.
I personally have not tried the 240GB HDD upgrade.
Edited by Communism - 4/17/12 at 10:22pm