With the refresh rate of 60Hz of most LCDs you will either have a fluid stream of 60, 30, 20, 15, etc FPS.
Does 100 FPS help on LCDs? No, refresh rate is limited to 60Hz, thus not capable of showing more than 60 FPS. BUT! A game running at 100FPS will usually not get slowed to less than 60FPS. If you run normally at 60, you will get slowdowns from time to time to less than 60 fps.
Is 45 fps better than 30 fps? No, not really. Since the screen refreshes 60 times a second 45 fps will have some frames aligning to the refresh rate and some not, thus giving a mix of 60 and 30 fps.
ex:
Code:
60 FPS: 1 1 1 1 1 1 1 1 1 1 1 1 1 1
30 FPS: 1 0 1 0 1 0 1 0 1 0 1 0 1 0
45 FPS: 1 0 1 1 0 1 1 0 1 1 0 1 1 0
1 means there will be a new frame on the "Hz" screen refresh, 0 means there won't. The difference between.
If you drop below 30 fps the things are gonna get ugly with 60Hz screen.
So what matters to you?
The human eye is very adoptable. If you are used to 30 FPS while playing you have no problems playing very well at 30 fps. The hugest impact on aim is human reaction and latency and the difference between 30 and 60 fps is minuscule. (difference between a second frame in 60 fps and 30 fps is 16ms, every other frame will be 16 ms slower on 30 fps).
If you are playing games like Dragon Age, WoW you can come a very long way with 30 FPS or even 20.
The only problem with a game that runs in 20/30 FPS normally will have dps dives under graphic heavy sequences/areas.
Like my MBP that can do almost 100 FPS most places still did drop down to like 20 FPS at first boss in ICC25 and I know people that had machines that normally did 20 FPS that crashed or lagged out the same place.