So i guess they change it. then the summon is the one to take hits, and probably, when we use the special skills, it will cause the summon stats damage.
I know that when you used a summon skill while riding it consumed your SP, but only by mounting it the SP/sec consumption is 30% higher than with it only summoned.
On a side note, summoner builds would rely more on support classes i think, what i mean is, if you take any dps class, you will have a even greater SP consumption, but if you take Alch for example, as long as you have ingredients you can even leave your summon attacking while making pots, linker is also a good class to go with Sorcerer, even tho they nerfed Joint damage to half, since the higher INT you have, the harder your summon hit, i think summons can get buffs too, unless they changed it, so chrono attack speed buff would also improve its attacks.
If you will go with offensive classes on your build, i would suggest not use ride, first for its consumption, second because while riding you can’t use your other skills except the summon own skills.
Note that i am saying what i experienced on iCBT, since kOBT is being updated fast i am not sure about the current state of some circunstances.