I would say that it is almost steep enough to glissade in places. So, no I wouldnt bet on your buddy keeping up, but wouldnt be too far behind. Mostly cloudy with chance of showers at this time of year up there can mean just about anything, but a lower freezing level for the ledges is one thing in your favor. Colchuck is in this time of year rather than a roll of the dice on Rainier.
My .02-I'm sure others have other things to say
TTT