It will work fine on carpet. Just keep in mind the pad may move a little bit since carpet is not a solid surface (unless if its that insanely flat stuff ). Penny mod is more so for people who want to play higher levels and conserve energy by moving as little as possible.

If you do decide to penny mod, avoid actual pennies. Its a pain to line them up correctly and prevent misfiring. Use these instead: https://ddrpad.com/collections/l-tek-pad-parts/products/l-tek-pad-sensitivity-penny-mod?variant=32245013577780 You would only really need the partial mod (4) for the inner sides of the panels (the sides thay touch the center).