Why use Braid to Fluoro or mono?

I fished for many years using mono, then tried some braid and saw the benefits.
After a long time off, (not fishing due to life responsibilities) I see that now there is a trend for using braid with a fluorocarbon leader to achieve (apparently) the sensitivity of braid feel (no stretch) with fluoro "invisibility".
We can argue all of the points on each but I'm asking as an avid sportsman prefering to use the best available when reasonable but having not kept up on the transition to this system.
I fish 100% fresh water, all species from bluegills to pike/musky, use both baitcasters and spinning gear. I prefer to cast most of the time but I do troll when appropriate. I'm not a catfisher and while I would like to fish for salmon, I'm in the middle of the country where that opportunity doesn't present itself.
The best simplified explanation of this setup has been here 
Since I've recently tried this setup, having tried to educate myself of the benefits I have the following questions.
1- Is it worth the effort to use this type of setup? It seems overly complex to have to tie a "brittle' fluoro to braid knot leader that has to travel through rod eyelets weakening it with each cast
2- Since most of the freshwater fish rarely take more than a few runs most spools are filled with backer or primary line that never see's the light of day past 50 or 75 yards. Many 2500 to 3500 series spinning reels carry from 200 to 400 yards of line likewise baitcasters carry at least an extra 50 or more yards of "spare room". Would it make sense to just use fluoro on the last 50 yards? If fluoro is as superior as suggested to mono, and if (as I suggest) having to cast a knot through eyelets weakens the knots ability, then why not eliminate the damaging portion by placing the knot back where it almost never sees the eyelets.
Has anyone done a study on the knot strength of Fluoro to Braid after 100's casts through eyelets and dragged through sand and rocks? I know regular checking is important but retie-ing 20 pound slippery braid to 8 pound fluoro isn't as easy as it appears on YOUTUBE when they show you with 100 pound HiVis.
 
Any contributions, comments, suggestions, experiences appreciated.
 

I use 12-24" of flouro at the end of my braid for most freshwater applications. Uni splice, micro swivel, or Albright knot depending on application/line diameters. I don't cast the splice through the guides typically.

I have had it fail, but very likely from user error, not wetting the line enough, bad leader material or just too light of leader. I switched from a surgeons knot that was failing way too often. Good knot for mono to mono or floro, doesn’t seem to work well with braid for me at least. The amount of times that I have had uni to uni fail in comparison isn’t close. I can’t recall having it fail on heavier setups. I think many are when I size down leader when bite is slow and forget to adjust my drag to make up for it.

I use a 3x or 4x surgeons knot for braid to flouro. I feel like this is not a very popular knot to use for this purpose and I can not for the life of me figure out why.

It is SO much easier to tie than any of those other popular knots, like the double uni, or FG, or a blood knot. And it’s pretty damm strong. When I have to break off, 90% of the time the knot at the bait fails before the knot at the leader, and I use a palomar for the bait which is also a pretty reliable knot.

Maybe it’s the profile, and it doesn’t go through the guides well enough for some people?

Conococheague
I use Fireline with a fluro leader and when I 1st started using this setup I quickly discovered that Fireline is abrasive and when it is tied to fluro, it will cut thru the soft fluro like a hot knife thru butter as soon as pressure is applied. Bye bye fish and lure. I soon learned to use a tiny swivel to connect instead of knots and this works fine, you just have to remember not to reel it thru the guides. Learn to make all casts with the entire length of leader dangling from the rod tip. 

What sizes are you using? I think the slice through is more of an issue on light lines, at least for me. I had horrible issues with 4# leader on I think 10# braid, might be thinner. I’m talking panfish breaking…. This was using surgeons knots. My guess is they weren’t tight enough or friction burn from not wetting or pulling knots too fast. I’ve pretty much changed my leader material to 8# or higher now. I haven’t trout fished since, but if I do, definitely doing the swivel thing. I did this for panfishing a little until I just went to 8# leader and fish didn’t seem to mind. Helps me get out of some thicker weeds and timber too.

Not as much of an issue on heavier lines but I had and was enough. After losing 3-4 wipers fishing with Pensfan a few years ago, had me swearing off the surgeons knot. Since changing to uni to uni, which is just as easy to tie as the surgeon after practice, I rarely have knot breaks. The ones that I do, I am betting had to do with either not pulling them tight enough or more likely not wetting enough and pulling too fast. I just get too antsy tying when the fish are biting. Nothing beats the feeling, but turns me into an impatient child rush the tying. I’d bet 90% of my knot fails were tied a few minutes after getting a bite. The ones that I tie at home seem to work great. Go figure.

Mine are all powerpro. Except one rod, I have the Yo Zuri. It was power pro that I had issue with the 4# leader and at times 6#. I’ve had good luck with 8# leader on 10# Yo Zuri. I’ve caught countless hybrid stripers up to 30” without issues.