The whole idea of a recovery partition is to hold the required info needed upon the dreaded later date. If you're using recovery CDs and/or OS from the OEM vendor, it should automatically make it back to the day it was made at least big name vendors. Just follow the prompts or guide for a true mirror image of what was on that 1st day. Also, I'm sure there's a finite space required, so reducing it too small isn't going to help maybe hinder the process. If this all to just gain more space, is the 600mb worth that much trouble, maybe better to get a larger HD if possible.
Does it matter how much unused space there is on the recovery partition? I don't see where it would matter but would like a second opinion.
I made the recovery partition on the new hdd about 600Mb smaller of unused space then the orginal. So now it has 517Mb of unused space vs about 1.2Gb