I know for most things IDE is fine on the Mikrotik router. Running a proxy is different though.
If one has a 10ms seek time at very best case on a single IDE drive you cannot excede 100 requests a second. So supporting an array of 2 - 4 SCSCI drives would be great. SCSCI works better even with a single drive for a caching proxy anyway. Of course supporting multiple IDE drives for cache would help to but IDE would not support many drives like SCSCI.
Matthew