Fans always on in Boot Camp I have a 2015 Retina Macbook Pro 13″ running Boot Camp Windows 8.1.

On default settings, the fan seems to idle at 0 according to "Macs Fan Control", and then slowly climb when it reaches 70℃ or so. Gaming makes it go around 102-103℃ max, and hover between that and ~90℃.

Lubbo's Fan Control seems better at gradually increasing and decreasing fan speed, but it as well as Macs Fan Control seem to stick the fan on always on with a minimum of 1299 rpm, once I enable them to override the stock fan management. 

In deciding how to modify my system I wonder if OS X always keeps them running and if that is bad for the machine long term compared to windows drivers behavior?
You are correct that OS X always idles a blower/fan if they are present. 

I thought it was always 2k RPM on stock hardware, but you might be correct on the 1300 RPM number - I don't have data on that specific hardware.

I doubt it's bad since Apple selects the components and probably has really great data on what percentage of failures are due to manufacturing variations and which are excessive wear on the components.