Given the release of at least one new suspension mount (K-Tec Nautilus), of all the current mounts which one do you think provides the best isolation? This will be used with a long line gradient mic.

Either the Rycote InVison the K-Tec Nautilus, provided the correct model for your particular mic's weight/length is chosen.
If I was currently in the market, I would try the K-Tec. They are competitively priced. The K-Tec is made in the USA and Dave & Co. are nice folks as well.

After reading the marketing materials on the Nautilus and some reviews I've decided to pass on that one but they have a couple of other options that look like they would work well.

Technically the Rycote "Lyre" is the best there is.

Talk to Rycote and get the best one for your mic.

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