According to Everbuild,
https://www.everbuild.co.uk/wp-conte...IXALL-V1.1.pdf , Stixall's elongation at break is "greater than 60%", whilst the Shore hardness is 55-60, and the tensile is 'greater than 1.5 mpa' (218 psi).
According to 3M,
https://multimedia.3m.com/mws/media/...-tech-data.pdf , 5200's elongation (I assume 'at break') is between 762 and 805%, depending on
environment, with a Shore hardness of 68, and the tensile averages about 675 psi.
Based on that, it would seem that Stixall is a little softer and (probably) a lot less 'tough' than 5200.
For permanence in a
marine application, I'd probably go with the 5200, but at 4.00 a tube, a real world test would be easy to perform, at least for future reference.