A few tidbits from the Michigan experience-
The vast majority of crossbow users were already bowhunters. From the research survey ordered, 74% of crossbow users had used a compound or traditional bow in the previous 3 seasons. Only 19% were firearms only hunters only, before using a crossbow and 6% of crossbow users were new to the sport (mostly youths and women in my anecdotal experience).
During the year before crossbows were legal, bowhunters using compounds and traditional bows showed a 42% success rate of taking at least one deer. In the 3 years of legal crossbows, crossbow users had lower success rates, 36%, 36% and 39% (2009-2011).
A couple other highlights from the study...
The number of people using crossbows jumped from roughly 46,000 in the first year after legalization to roughly 74,000 in year three.
In 2009, crossbow hunters killed 24,882 deer, or 5.6 percent of the 444,231 gun and bow total.
In 2010, crossbow hunters killed 38,310 deer, or 9.2 percent of the 417,850 total.
In 2011, crossbow hunters killed 54,902 deer, or 13 percent of the 422,014 total
The average age of all Michigan deer hunters is 42 and the average age of the Michigan crossbow user is 50.
After age 48, the majority of those hunting in archery season are using a crossbow. By the time they hit age 60, the ratio is roughly 2:1 in favor of crossbows.
From ages roughly 12-30 years old, the numbers are flip flopped, with those using compounds and traditional bows far outweighing crossbow users.
For adults, the ages with the highest usage of crossbows was ages 52-54. For compounds and traditional bows, the highest usage per age group was ages 39-41.
In 2006 (before crossbows legal), all Michigan deer hunters combined killed 691,000 deer and all archers combined killed 309,000 deer.
In 2011 (3 years after crossbows legal), all Michigan deer hunters killed 648,000 deer and all archery hunters killed 321,000 deer.
Other studies have shown that the typical deer hunter, considering all the fair weather and casual deer hunters, wants roughly only one deer for the freezer, per year. Freezer space is a consideration, on top of most deer hunters only eat venison on occasion. So knowing that, it appears that if anything, that crossbows have shifted 4% or 5% of the harvest from firearms season to archery season.
This is just my assumption from working at Cabela's, but with all the gray beards buying crossbows, I noticed few of the older guys wanted to climb a tree with the crossbow and add on sales of tent blinds was huge. My assumption is, many of these guys, while still having a pleasant day afield with their crossbow, have found that killing a deer from the ground, with wind and movement concerns isn't as easy as killing one from a treestand.
In my opinion, that's why the numbers are going to be a wash, in Michigan. Also, in Michigan deer baiting is huge and the older folks bait in higher numbers. If I was to guess, 90-95% of those guys 60 and older, using a crossbow out of a tent have some type of bait dumped. But what those guys will also find is, bait at 25 yards when you're at eye level isn't the same as bait out when you're 18' up in a tree. My guess is, lots of guys are busted my spooky Michigan doe's on a pile of beets and carrots, making the kill numbers about equal.