I take no issue with using a bead so long as your gun shoot true to point of aim. But the reality is, many do not. It's rarely noticeable when wing shooting because the pattern size compensates for slight variations in where the true center of the pattern is. But you choke down a turkey gun, particularly with many of the good loads today that shoot very uniform patterns, and it often becomes noticeable. If half your pattern is hitting high or left, it wont take much to miss a turkey. So adjustable sights are sometimes needed.
I've used rifle sights and like them fine for turkeys that are standing still. But lining up a rear sight and front sight and getting a clean aim at a running turkey aint easy, even for somebody with a lot of practice using rifle sights. I was hunting with a buddy who crippled a turkey once. I had a plenty-good opportunity to kill him running away but drawing quickly and trying to get everything lined up for the shot was tough. I missed (badly) and we never found the turkey. I could have missed him with anything, but I don't think I would have. So I switched to a reflex red dot and absolutely love it (Burris Fastfire III). 3 MOA dot is more precise than a beed, no magnification, and unlimited eye relief. Clean sight picture, easy target acquisition, and instinctively easy to use on a moving target. I left one on my .410 (because I didn't feel like taking it off and putting it back on) and shot doves with it this past fall. The only drawback I have found is hunting in the rain. Water beads on the glass make it tough. I killed a turkey in a severe thunder storm last spring, but when I drew down and had to REALLY work to make out his blurry red head and line it up with my blurry red dot, I would have really loved to have only a bead or rifle sights. Battery was one early concern. But they last for thousands of hours and most models have an auto shutoff feature after 10-12 hours, so that's been a non-issue. Out of an abundance of caution, I just put a new battery in at the beginning of each spring. Also, the reflex sights can mounted very low atop the gun for better shooting form and easier aiming.
When you say red dot, I assume you mean a tube-style scope with a dot reticle. (Many people use "red dot" interchangeably with the reflex sights). Someone may give you a "pro" list for them, but I don't know of any - except they are often cheaper than reflex style sites. They are bulkier, a little heavier, have a more limited field of view since you are looking through a scope tube, and they still have the same drawbacks with quick target acquisition, water on the glass, and need for batteries.
:2c: