I thought I'd chime in here. We are Yakima all the way (since 1982). We almost always have one or two long open-top fishing kayaks on the roof when we take trips, and they are wonderful once they are on the water, but way too heavy on land. We always take them down to pop the camper up. I have always used the original yakima kayak saddles or in recent years the Makos, and never had a problem. But I'm anal about my tiedowns, even use a third middle bar for the just-in-case strap across the middle of the boat. It's pretty heavy up top just with empty racks. I check all the straps at every pee, gas, and taco stop. We always seem to drive in some kinda nasty winds at some point in our travels.
This November I decided to try traveling with the hully rollers to hold the stern of a 15 ft O.K. Trident. I never liked how the hully rollers supported that particular hull, but it is way easier to take the boat off the back of the rig with those,so figured I'd give it a go on the first day of our trip, all highway, 60-65 mph driving. We encountered some strong cross- and headwinds thru the Owens Valley and high desert. At the gas stop where 395 joins the I-15, the straps on the stern of the kayak had loosened up on the hully rollers, and the boat had jumped off the rollers and was sitting sorta crooked on the rear bar. It coulda been ugly out there on I-15 a little later, duking it out with the semis, if that boat had left the roof. Needless to say, I put saddles back on the rear bar when we got to San Diego.
A couple of days later we were slammed by the strongest crosswinds I have ever experienced up on Tecate Summit east of San Diego on Interstate 8. The fore and aft mako saddles held brilliantly, but we pulled off on the shoulder and crept slowly for a couple of miles, along with those semis.
So just wanted to warn the folks using the mako/hully roller combo for their kayaks, man, take it easy in the high winds, and check your tiedowns often. The yakima bars on the long tracks are the way to go for boats, factory aluminum square racks, maybe not.