While I definately agree we have more than enough inventory, I actually run a bit closer to mid-upper70s/80. That being said, I use spellcast and generally have most of my gear sets with me at any given time.
8 Staves (Kirins Pole, + Elementals minus Fire/Water which are in Satchel)
6 Grips (Ice, Wind, Dark, Staff, + Bugard Leather +1, Raptor +1)
2 Ammo (Hedgehog + Phantom Tathlum)
6 Hats (Argute, AF+1, Elite +1, Turban, Goliard, Errant)
9 Necks (Caract, Uggi, Elemental, Dark, Enfeebling, Grandoise, Orochi, Enlightened, Enhancing)
7 Earrings (Loq, Morion+1, Moldy, Dark, Elemental, Antivenom, Boroka)
7 Bodies (Errant, AF, Argute, Goliard, Vermy, Royal Red, Morgana)
5 Hands (Argute, Vicious, Yigit, Garden Bangles, Genie)
8 Rings (Jelly, Omega, SnowX2, Troopers, Ether, Electrum, Insect)
5 Back (Gleemans, Errant, Prism, Cheviot, Invigorating)
6 Belts (Swift, Penitents, Heirarch, Hyorin, Anrin, Rairin)
4 Legs (Argute, Mahatma, AF, Yigit)
3 Feet (AF, Goliard, Yigit)
With that, I still have 4 slots for random things in my inventory, not to mention another 80 slots in my Token for food, meds, and other pieces of gear that I wont necessarily need but may want just in case. Bolded are the pieces you were asking about. I feel that these Obis are a must for SCH. I also feel that due to the frequency we use Gravity, Bind, Sleep, and Aspir/Drain that Dark, Ice, and Wind Grips are important to SCH. Keep in mind these grips also help reach a 320/120 set for nuking higher resisted mobs and generally the +2Macc > 1INT for resisted nuking. I also keep Thunder Grip in my satchel for this purpose.