I haven't benchmarked them specifically but I don't think there's a difference in terms of I/O or CPU. At least I haven't noticed one (we've switched to a 64bit

I haven't benchmarked them specifically but I don't think there's a difference in terms of I/O or CPU. At least I haven't noticed one (we've switched to a 64bit image a while back). FWIW, we run a mid-sized deployment on EC2 (~60 instances) and anything interactive has to go on at least m1.large and up (usually xlarge). We do use m1.small's for queue-workers and low priority batch jobs.