So, six months on, I've still not sorted myself a new flex-top 460 RDM for my SF 7.0. (Thank you by the way to all those who have contributed responses to my original question, or other useful responses).
Buying in the UK, there seem to be a limited number of potentially suitable (flex-top) options for 460 RDMs available, including:
The Unifiber 460 RDM Evo 100 Flex-Top. Consensus seems to be that would be a reasonable option.
Simmer RDM 8 / 10s; The Unifiber mast selector chart suggest they should match reasonably well, but 'Newfreakuser' reported a less-than-great experience.
RRD RDMs. Again, the Unifber chart suggests a match, but I can find no other information on their bend curve or compatibility.
Goya RDMs - Again, the chart suggests a match.
Chinook RDM 460s . CalebChinookRD reported that despite being nominally Constant Curve, Chinook RDMs "generally err on the flextop side". I'm wary of the CC designation though
Any more insights or experiences anyone? I'm leaning towards the Unifiber, though there are some reasonably priced RRDs around.
Obviously a Hot Rod would be the ideal, but there seems to be very limited availability in the UK and I am not sure I can justify the premium price for an occasional use mast.