In area or volume? That's some very precise measuring and it must have taken a long time to check every single figure. I'm not sure about the percentages, but there are at least a few Hot Toys figures that look like unnatural pin heads with bodies far too big for their heads. YMMV.
Not sure that "about" translates into "precise" or where the logic would be in my pulling out head sculpts and carefully measuring them against one another, but OK. I do, however, have an educational and professional background in both art and design and human anatomy so I have a pretty good knowledge of what constitutes relative size differences. I also have roughly 50 Sideshow figures and at least as many Hot Toys and in general Sideshow's head sculpts are let's say in the neighborhood of 5% larger. There may very well be +/- variations in that range, but unless I missed something I never said it was based on an empirical comparative study.
Yes there are Hot Toys pinheads for sure. Dutch comes to mind as well as G.I. Joe Roadblock -- I ended up swapping out the former, and never purchased the latter due to the inaccuracies in both head size and body type as well as limited interest in the film franchise. I also stated that Hot Toys head scale "might" be slightly idealized. However since I'm not going to take the time to carefully and precisely measure each actor and compare their head-to-body ratios, we'll just leave that in the "possibly" column as I would not want a casual word to be misconstrued as a statement of scientific fact.
But this is not a Hot Toys vs. Sideshow bashing exercise. I support both companies. There are really two points that I was making (from my personal opinion).
Point #1. When Sideshow was selling their 1:6 figures for $100 or so, I could be more forgiving of poor paint apps, looser sculpts and the relatively larger head size (the latter of which I know is based on their house scale when they started the line and HT either didn't exist or may have been just a small start-up). Up until a year or so ago SS's 1:6 figures were approximately 1/2 to 2/3 the price of Hot Toys (I'm not including large or complex figures like Iron Monger or Raynor). So if Sideshow is now going to charge $200+ for a figure one would expect them to deliver a figure of comparable or better quality to justify such a price hike. Right now there's an appearance of "this is where the market seems to be".
Point #2. Sideshow an Hot Toys "seem" to have entered into a gentlemen's agreement with the 1:6 Star Wars line in terms of reciprocal distribution, and to a degree, character selection. I think that's a good thing for collectors. What would be great (again in my opinion) would be to have the lines work together even more seamlessly, especially since the figures are now at a similar price point. To me that would mean head sculpts that are closer in scale, sculpt style and paint application as well as high quality tailoring. I would like to be able to display the lines together and not see glaring variations between pieces. Further, if both companies have agreed not to step on each others toes too much in terms of character selection (as HT apparently indicated in regards to R2D2) that should translate into a broader character selection (i.e. SS may end up focusing on droids, non-humanoid aliens, creatures like Taun tauns, helmeted soldiers like TIE pilots and Royal guards, environments, and PT characters, which would free up HT to focus on OT humans, essential characters like Vader, Boba, Yoda and Stormtroopers, and Ep VII-IX). Maybe that's wishful thinking, but to me that would be a nice compromise between the two companies, and would help alleviate the guessing/waiting game in deciding which company to buy a $200+ figure from.
Note: Photo is Just for comparison of a Luke vs. Luke vs. Luke. I fully know the first SS is an older sculpt that was in the $70 or so range. The SS Hoth proto certainly looks miles better, but need to wait for an in-hand production piece to see if it's $200 worth. I hope so, which is why I have not cancelled. But I still think the HT looks better than the SS Hoth but will have to see.