I have been using flask camera's for a good 10+ yrs now, and also have IR camera's
to me, I get just as many pic's of deer looking at a camera flash or not
many IR's make a sound when they take a pic and many also give a glow
all things can cause a deer to react to that stuff

I get tons of great pictures at night with my flash camera's love the quality of pictures over an IR a lot , IR's to me such on any thing that isn't standing completely still


the only draw back I have about flash camera's is they are EASY to be found at night by crooks
them flash's on my cuddleback attack's can be seen no lie 500+ yrds away on a field edge set up
and probably one main reason I get so many stolen over the yrs,
so on public lands, thats a risky deal
as I am on heavily posted lands and still have them stolen every yr

I have to really bolts and make taking them super hard
so those would be the only draw backs to a flash over an IR camera in my eye's
but I do not believe they spook any more deer than an IR camera
I get thousands of pictures on my flash camera's too, so??