I would think of no surplus as a rested bonus in other games or you will find the time you can play without any surplus since they practically doubled the sp gain is very little.

But as other said you will need to level multiple classes to be truly effective anyways. So why not level multiple classes at once.

Conj to be able to cure yourself and get protect, shell, stoneskin, and shockspikes. (this helps out a ton solo and in a group when you are missing a healer)

Thurm getsmp management abilities, a regen cure ability, a move that converts dmg you take into mp and another that converts dmg you take into dmg the mob takes.

Archer gets attack buffs and hate removing abilities
Lnc gets attack buffs and strong debuffs/buffs (some are LNC only though)
Glad get accuracy buffs, defensive abilities and hate grabbing abilities
Pug get a healing ability and hate grabbing abilities
Mar gets a healing ability, defensive abilities, some abilities that lowers the mobs def and evasion, and some hate grabbing abilities.

So what I would do is figure out what you want to be a tank, Range DD, melee DD, support, healer, magic DD (although they are sorta weak atm), or sorta a hybrid.

At that point level the classess to get the abilities to build your job. To be the best of anything you need some things from everything basically.

This should give you at least 20hrs depending on how many classes you are leveling with no surplus a week. Past that point you will have to deal with surplus stage 1 which is not an issue at all 10% loss, the fact people are complaining about it is sorta ridiculous when losing a rested bonus on other mmos is a 20-50% sp loss yet no one complains about those at all.

The only time surplus is a real negative is if you are a hardcore 40hr a week player and you are only leveling up one class... then you might hit 40%+ sp loss with fatigue