Hi Andreas,
Sir, you are a genius.
That migrate option was not obvious until I went looking for it... This seems like a most reasonable approach and does not scare me in the slightest.
Excellent - I can now present a couple of workable options to the company network-meister. I do not see any problems with either, but a choice is nice and neither will actually cause him much work. I'll be next to him with my laptop onto ESX (I have a backup route in to ESX so am not dependent on these links running for management purposes) so we can do the reconfig together (and back out sharpish if something goes bang).
Many many thanks,
Tim