I don't know if any coins actually using mimble wimble right now, DCR could effectively be the biggest coin doing it in the early going.
DCR is having some good growth, and with the increase of daily volume I am expecting we will once again achieve our all time high.
Bitcoin is now stable, so the confidence is back, people are investing with crypto and we have seen some of the crypto coins have consistent growth, one good example is MGO which is now at top 100 and from over 1K sats now at 11k sats in just a short period of time.