I have down firing subs on a wood floor with a rug in front of the speakers, and a thick rug mat. I also found that isolating the sub and adding a second sub made big improvements. In my limited experience, I haven't found a difference in the front firing sub I've tried.
Rather than a subdude pad, I used feet. SVS makes sub feet, but I went with platinum silicone isolation feet from Hudson Hi-Fi: https://www.amazon.com/Platinum-Silicone-Hemisphere-Isolation-Durometer/dp/B075KM5Y8W/ref=sr_1_3?dchild=1&m=A3DXW0NUYLHI2J&marketplaceID=ATVPDKIKX0DER&qid=1588947657&refinements=p_4%3AHudson+Hi-Fi&s=merchant-items&sr=1-3&swrs=C706340B8638275BE0014217667F93CC
Rug mat: https://www.amazon.com/gp/product/B01HN8MC4S/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
Rather than a subdude pad, I used feet. SVS makes sub feet, but I went with platinum silicone isolation feet from Hudson Hi-Fi: https://www.amazon.com/Platinum-Silicone-Hemisphere-Isolation-Durometer/dp/B075KM5Y8W/ref=sr_1_3?dchild=1&m=A3DXW0NUYLHI2J&marketplaceID=ATVPDKIKX0DER&qid=1588947657&refinements=p_4%3AHudson+Hi-Fi&s=merchant-items&sr=1-3&swrs=C706340B8638275BE0014217667F93CC
Rug mat: https://www.amazon.com/gp/product/B01HN8MC4S/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1