Okay, I can see there's some BS statements in this one. So let's clear things up shall we?
Note: When I write real FPS I will be referring to the lower out of game FPS or monitor FPS. Aka the amount of new frames actually displayed on the monitor.
First of, the visuals. Let's say you change from lower to higher polling rate.
The movement of the cursor will not look smoother at all UNLESS your real FPS is higher than the device with lower RPS. Because, If the RPS this is lower (not likely, since most monitors are 60, some 120 FPS), you will get multiple frames within the same report from your tablet. But if it's higher you will already get the new latest poll's positions displayed.
For the delay, changing to a higher polling rate, assuming that nothing else is changed (input lag), there will be a minor improvement. But changing to a tablet with higher RPS will not guarantee a shorter delay.
However, increasing RPS will make the cursors movement smoother, even for the case when it's not improved visually. This should increase accuracy, by improving consistency, for the moments when your cursor enters/leaves a circle just before/after you click it.
My thoughts on higher RPS?
I don't think it will help very much, though I would like a high RPS tablet myself. More RPS is better, in all cases (speaking generally, it could make you miss a note you would hit with lower RPS, but it's not as likely as the other way around).
However, what should be more important for playing osu! is, getting as low lag as possible when it comes to:
Delay between tablet and computer. Delay between computer and monitor. Delay between computer and speakers.
And then there's higher FPS monitors. If you're playing on a 60 FPS monitor I would recommend changing. People on some threads claim that it will not make any difference whatsoever. That's not the case... Increasing real FPS will improve the smoothness. I recently changed from 60 to 120 FPS. What especially gets affected by this is the cursor movement. While moving something small over the screen at high speed you can see clearly all the places it's been displayed in, improving real FPS will make the space between these locations smaller. 60 -> 120 FPS will cut the distance in half. This will increase the speed at which you can move your cursor without detecting these gaps to the double. And it will make it look smoother at all times.
Note that a higher frame rate for your monitor will only affect the game if it runs on higher FPS than your previous monitor's frame rate.