It depends on the script... I use P&P and that isn ot compatible with mIRC 6.1.. The script works but there are some bugs do to changes in mirc... You just have to try and see for your selves... Whick script do you use btw?
best thing to do is read the versions.txt available online at http://www.mirc.co.uk/whatsnew.txt to see if any scripting changes may effect you. If you are unsure, put v6.1 in its own directory to test. Hard to give you any other answer since everyone uses different scripts.