I'm running my IRC client and log storage out of this instance, and while it would be nice to be able to have more room which is cheaper, what happens if my instance is ever stopped, or needs to reboot? I thought the whole point of EBS backed instances was that the data storage was more permanent.
Reboot doesn't erase the ephemeral disks. Stopping (by you or by Amazon due to hardware failure) erases the ephemeral disks.
I see no point of storing blockchain and IRC logs on EBS. You pay both for space (per GB) and accessing it (per I/O). Blockchain is easily replaceable, store it on a local disk where both space and i/o are included in the price of the instance. IRC logs should be compressed and stored in a way that makes them hard to accidently erase or alter. So store them in Amazon S3 or RRS or Glacier.
Basically you'll need to set up a sensible backup schedule for your instance. Use the ec2-make-ami as a backup until you'll learn how to properly operate everything and make minimal backups.
You can also have both local and EBS storage attached to your instance and size the EBS appropriately to the task, the smallest volume is only 1GB. You can have both combinations: boot from local disk and attach EBS or boot from EBS and attach local disk. But your first investment should be to read the available documentation, the pricing plans and the invoices you are getting.
