I have the Laguna 18BX and one of the many features that caused me to choose it was the brake and I have been happy with the decision ever since. The brake is a great safety and convenience feature and well worth considering when it is an option.
It can be surprising how long the blade can continue turning once the machine is shut off and how quiet it can be. Should you make a cut and shut down the machine, then return to make another cut before the blade has stopped, it is entirely possible to make inadvertent (and painful) contact with a blade that doesn't know the difference between flesh and wood.
If making multiple cuts using a variety of settings (height, fence, etc.), the brake can save a lot of time over waiting for the blade to stop before making the adjustments, or for removing small pieces that are sitting close to the blade.
If using two hands to make a cut partially into a piece of wood, it can be easier to step on the brake to stop the machine than taking a hand from the workspace to activate the shut it off (and associated wait time for the saw to stop) before backing the workpiece out of the wood (and possibly pinching & pulling the blade from the guides).
During some processes, I will start on the infeed side of the saw and end up on the outfeed side to finish the cut and the brake is convenient for shutting the saw off vs getting back around to the switch. This activity is also one of the reasons I chose the the Laguna over other models as both dust collection ports are on the same side of the machine and out the workspace, unlike some machines that have dust ports on two different sides.
Depending on what I am doing, I use either the switch to shut down the machine or (most often) the blade brake applied with just enough pressure to slow and stop (not causing an immediate stop).
Of note, when my machine was new, I found that the pedal was tight enough that it didn't fully raise once activated and thus the saw would not start due to the lever not contacting the shut-off switch. A gentle toe under the lever easily raises the pedal should it be necessary. It wasn't long though until the machine became broke in enough and this was no longer an issue.
I did a lot of research and was hands-on with a wide range of machines (Rikon, Jet, Laguna, King, others) and for my personal use I really liked the Laguna and have never had any regrets in going with it. Each user is different though, as are individual preferences to various features, which makes having a variety of options available a plus for each user to choose from. As far as cost, having the brake was worth the additional funds and I have a machine that I use with pleasure, never stopping to think back to "what if...".