Every OHC engine I've ever worked on has you set the valves cold, since you can't set them hot without burning yourself, but since they don't have pushrods there is less to go wrong. The SOHC and DOHC engines also have much tighter lash than an old stovebolt.
I think some of it is going to be how much the differential expansion between metals is going to be between cold and hot lash, and some of it is going to be how much the oil film on the lifters and cam bearings differs in thickness between cold and hot.
You ought to be able to get it really close cold if you precisely measure the lash on your particular engine after you have adjusted it hot and let it cool down to a reference temperature, and then make sure it is that temperature if you are going to adjust them cold. But really, how hard is it to adjust them hot? Its not like you are adjusting a flathead or a volkswagen, these adjusters are pretty easy to get to.
I think there is more error sneaking in there by making sure you are exactly on the base circle of the cam than the error you get knowing the cold numbers for your particular engine.
