It's easy enough to just time the pre and post capping times on natural sized cells. I've done it many times and no one who has tried it has reported any different results than I have see, or that Huber saw on natural comb back in 1791:
http://www.bushfarms.com/huber.htm#eggtoadultKeep in mind that on the 1st day no time has elapsed and on the 20th 19 days have elapsed. If you have doubts about this add up the elapsed time he refers to. It adds up to 18 ½ days.
"The worm of workers passes three days in the egg, five in the vermicular state, and then the bees close up its cell with a wax covering. The worm now begins spinning its cocoon, in which operation thirty-six hours are consumed. In three days, it changes to a nymph, and passes six days in this form. It is only on the twentieth day of its existence, counting from the moment the egg is laid, that it attains the fly state."
François Huber 4 September 1791.
If you shorten the pre and post cappings you will get significantly less Varroa. If you go to natural cell size you will significantly shorten the pre and post capping times.
A true scientist would try it and find out for themselves. It's not difficult. You'll need an observation hive (which any beekeeper should have anyway if you want to learn about bees), some small cell comb, a notepad to write down when the queen layed the eggs, and a marker to mark a number or letter over the cell she layed it in so you can time it. Then note when it was capped and when they emerged.