Lezyne Slip Vs Speed

I know there are threads on this, but reports seem to vary quiet a bit. Anyone used both? Which one of two would you reccomend for airing up a disc on race day?

The speed chuck has worked much better for me. Unlike the slip chuck, I do not have to hold it with one hand while pumping up my rear disc!

I’ve used the slip chuck on my Renn disc. No problems with fit, though I do find that I have to hold it on with one hand and pump with the other.

Not my wheel, but an example to show clearance:
http://www.thetallcyclist.com/wp-content/uploads/2012/11/Lezyne_slip_chuck_hed3.jpg

I have both, I would definitely go for the slip chuck. The speed chuck started blowing apart under air pressure when inflating the tires after just a few months of use.