Mcr symptoms and conditions

I am a urologist. My 5 years old son is on singulair 5 mg since last 2.5 years. The only change I notice is spacing of attacks. I dont find that inhaled steroids can be stopped. He is on becotide 200 Mcr gms per day. In my opinion it is not a magic drug, just over advertised. I did not notice any significant side effect. I am just thinking to stop it this summer and switch to inhaled sodium chromoglycate. Am I right????