Vast difference
Well, I will have to say that the best low deflection cue compared to a plain jane 13mm maple cue plays vastly differently. My first experience with low deflection was in the eighties, a twelve ounce sixty inch snooker cue. I forget the size of the tip, I think 11mm or smaller, but I am here to say from end to end of a seven foot bar table it made over two inches difference in deflection sometimes! That puppy was a rare pain to learn to play with especially since I was only using it in one bar. However, when I got the way that stick played down I could make the old heavy bar ball do everything but sit up on it's hind legs and beg.
The huge difference, more important than deflection in my opinion, was total cue weight. I had speed control to a degree never experienced before. Deflection was certainly easier to get right, since it was maybe 1/4 the deflection of a standard bar cue off the wall.
An old master with his shaft he has used for years is rarely going to get deflection wrong. However, regardless of who you are, your errors are smaller when you are judging an inch of deflection instead of four.
The easiest way to get lower deflection is to take mass off of the outside of the shaft. That also makes it harder to play with so a combination of mass off of the outside and mass removed from the inside is often used. Got to pay the piper somewhere so the lowest deflection shafts have to get thicker faster for strength. Players have to compromise somewhere, either more deflection or faster taper. That in a nutshell is the answer to your question about taper Jack. People still like a pro taper best, but having to choose between lower deflection faster taper, and more deflection pro taper, most will eventually vote lower deflection.
Somehow, there is more to the equation than is usually laid on the table. The theory is the mass of the first part of the shaft, five inches or less I believe, is all that matters. However, I would bet the low deflection qualities of that plain wood twelve ounce cue against any cue shaft on the market today.
The low deflection shafts are easier to play with. For the vast majority of players who only play a few times a week that means they will play better with them. Even the pro's will eventually give up their wood. Carbon fiber is different and the first impulse is to not fight learning something they don't need. However, as more and more players switch to CF, more players will be beaten by CF. The changeover is coming. Hi-tech has been proven better for pretty much all other sports equipment, it is better for pool too. The only reason baseball bats are still wood in the pro's is that hi-tech would obsolete the baseball fields themselves.
I like wood, wood is good. CF is better.
Hu