Just get SCSI. Gets rid of your IDE bottleneck, performance can be as good as you'll ever find and it is widely available. Not as flexible as 1394 (no hot plug and all that), but a good solution for drives.
This is not true - there are plenty of hot-swappable SCSI devices on the market, and they've been around for a long time. I believe most of these devices use an SCA-80 pin connector, which is power and data in one. Typically used in RAID cabinets where data is striped across multiple hard drives. If one of them fails you can rip it out of the chassis, throw it over your shoulder, and slap a new one in without powering down. You can then run a recovery program to rebuild the data on the drive based on parity information.
