In any comparison between the two normal methods of roasting, that on a spit will be found superior to that done in an oven; this is because of the big differences between the two methods and has nothing to do with the kind of fuel that is used.
This fact is easily explained, for regardless of all the care taken with roasting in a closed oven it is not possible to avoid producing steam when carrying out the process. The effect of this steam is so much the worse the more delicate the flavour of the item being roasted and the more easy it is to ruin its quality.