I have the double pol on a 1/4" hose.. and have used it many times on other tanks. I usually make it an over nite project, and from experience, if filling while the ambient temp is going down, such as over nite, the fill goes somewhat faster, even when both cylinders are the same temps.
After the replies here, I also can see where filling thru the outlet valve will bypass the float type overfill protection. So the bleeder valve would have to be used for the vapor/liquid detection. If filling overnite, it could very well over fill, even tho the bleeder valve is not opened.
I'll post back on results if I do this top off.