I have had a totally opposite experience coming from TKD to Muay Thai. If anything TKD has enhanced and complimented my Muay Thai game. Let me preface with my TKD training experience. Probably a little different from what OP has had. I started my training in TKD with '88 Silver Medalist Sayed Najem (Canada) and lessons from '88 Gold Medalist William Cordova (Mexico). Talk about old school corporal punishment style training. Loved every moment of it. We didn't stress forms, we trained strictly for competitions. We referred to it as Olympic Style TKD. Then moved on and trained with world champion and now sought after MMA coach Michael Tang. Master Tang introduced me to the TKD Olympic Lopez family and I was able to observe and learn from them. After years of training and competing my hips developed bone spurs and required multiple surgeries, rendering me with limited flexibility and thus pushing me towards Muay Thai. Biggest obstacle once I made the transition was learning to use my upper body and punching. I quickly discovered while sparring in Muay Thai that my leg speed, accuracy, ability to counter quickly, ability to fight in closed or open stance, the use of both legs and knowledge to gauge distance and leg length, cover ground, skills all reinforced by TKD, gave me a solid foundation or even an advantage. I can connect my kicks with the top of my feet or with my shins. We were taught how to throw a kicks without telegraphing, and how to maintain speed and generate torque from multiple fighting positions. I'm 5'10" and weigh 156lbs. I can get a 300 pound heavy bag swinging in no time. I can't imagine training in Muay Thai without my TKD background. I highly recommend training in both styles.