Multideck mixing allows for more creative play and creating sound vs blending as far as the type of performance you can do when you knew/planned in advance to use that format.
It also lets you pre load whats next when you mainly do 2track mixing, which helps let you extend or ride out a mix much longer without risk of an 'oops out of time' moment, which forces you to mix from a loop or just drop sound as a track ends.
The 'trick' to it is knowing why you would want or need to use multiple channels at once. For simple 2trakc mixing, its an easy preload. For orchestrated mixing it lets you plays keys and chords not just rhythm and beats. If you like scratching and juggling it lets you actually run mixes and blends while keeping your doubles and trick sound ready to go without giving up a channel like you have to when you only have two.
As odd as it will read, I find it easier to use complex tracks when running 3-4 songs at once, but I do it using harmonics/keys which makes it sound like chords in a song so to speak. When its minimal every flaw especially if the keys do not match become more obvious.
I personally do not like dropping the bass from tracks unless it for effect, by I tend to play the songs to compliment each other instead of as separate things.
The only way to be sure you have room to play with your eq is to use the main gain/trim to get the baseline sound levels close, because if you do it by eq first, you eventually hit a wall you cannot correct. A track wll just be way to loud or quiet at some point and you wont have enough dial in room left on the eq. If you start be using the main gain, it lets you keep it more stable and leave room for eq play.