clasped around the insulation rather than directly around the pipework
This would clearly change the resonant frequency of the pipework and may explain why only some people get the issue.
Trying to decide between the 5 and the 7. The 7 would leave a bit of headroom and the 5 bang on the money for heat loss (measured) per the actual outputs that are in an excel sheet. Are many people still finding issues on the 7 with noise?