What... the 2705 RPM Panaflo is very quiet actually. I have one. It is hardly any louder than a 2000 RPM/80.5 CFM/38 DBA Thermalright FDB 120mm x 25mm fan (I have two of these as well). If noise isn't a factor then get two of these Delta fans.
Scythe S-Flex aren't very good choices for heat sinks. First of all the OP said noise isn't an issue, so that rules out S-Flex right there. Scythe Gentletyphoon fans are actually better for heat sinks due to the higher static pressure. They're more quiet too.
But as I said... go for Delta if noise is not a concern. If noise is a concern, then go for Panaflo 120mm x 38mm fans. I bought the 2705 RPM version because noise is a slight concern. I was shocked by how quiet this fan is. The hydro wave bearings are very nice.