I think it would be interesting but probably not of any real statistical value as not all people who stalk deer ,are on this forum. Many estates have good records going back generations which can be really interesting to compare estates and years as you can begin to identify trends in wieghts ,numbers ect, peaks and troughs from bad winters/wet springs.
If it was possible to get everyone to hand in a genuine return for a given season it would give the proportion of the different species culled by the different types of stalker which in itself would be of value, although i still suspect the weather would still be a significant player in deer control , in the form of winter deaths and foetal re-absorbtion