No talks of custom installs. Voiding warranty just isn't my cup of tea. 
That said, is there any hope that Apple will finally include an SSD upgrade to the 21.5" iMac? I'm very curious as to why Apple never included it as a BTO in the entire range. I understand space constrictions would prevent the 21.5 model from including a second add-on hard drive, but theres no reason not to be able to replace the current 3.5 drive, which is also a BTO option for the 27".
That said, is there any hope that Apple will finally include an SSD upgrade to the 21.5" iMac? I'm very curious as to why Apple never included it as a BTO in the entire range. I understand space constrictions would prevent the 21.5 model from including a second add-on hard drive, but theres no reason not to be able to replace the current 3.5 drive, which is also a BTO option for the 27".