Has anybody used Nike Triax CV10 or Polar S625X before? Which one is
better? Does the heart rate monitor of Nike has a lot of interference
with other heart rate monitor?

I have the Polar one. It is great and way more reliable than the NIKEcounterpart. I have been using the Polar for awhile now and am veryhappy with it. If you also do bike training, this polar hrm is awesome!The only drawback with the Polar HRM is its price. If you are abeginner and wanna get serious about running and training for someraces, a regular HRM will do just fine. As for gettting distance andspeed and other info during a training run, I think if spend the $isnt' a big deal, then get a Polar. I did test the NIKE model beforegetting the Polar and let me tell you, NIKE is not as reliable andsensitive as the Polar model. However, with Polar sitting at more than$350 a pop, it really scares people away!

but the foot pod of polar is so big!