The Grid Slammer pedal circuit is almost exactly the same as... TS9!
Well, to be honest, the diodes arrangement is similar to Timmy, so there is a little change.
In view of this, I suppose that it would add too little to the diversity of simulations.
There are, on the contrary, interesting and original OD pedal circuits that are not covered at all in the Helix at present, such as: Zendrive, Boss OD-3, Subdecay Liquid Sunshine, Crowther Cake Overdrive, EHX Hot Tubes, Skreddy Screwdriver, Marshall Bluesbreaker, Barber Gain Changer, Ibanez MT-10, Emma Reezafratzitz. These, imho, would add a great value to the Helix, specially when it is used as a multi-fx pedalboard with a real guitar amp.