hello mark, thank you. i also suggest to update to 261 version as i discovered a small issue on IE which may cause a double payment or double order.
if you get problems like described here:
viewtopic.php?f=5&t=1023with any payment failing due to it's internal validation problem - please disable OPC Tracking plugin.
we tried to add utm_nooverride to all of the payment methods that do redirect and return, so GA scripts would work much better. It works with paypal, it there seems to be problem with a few other plugins.
kind regards, stan